Aquinas’s Understanding of Religion

Abstract

Thomas Aquinas emerges as a remarkable figure whose significant literary contributions have had a profound impact on our understanding of religion. Drawing inspiration from both the Greco-Roman philosophical and legal traditions, particularly the influential works of Cicero and the rich Christian tradition, notably Augustine, Aquinas presents a comprehensive and nuanced approach to the multifaceted concept of ‘religion’. While his analysis often situates ‘religion’ within the moral framework of justice, highlighting its inherent concern with the relationship between humanity and the divine, Aquinas goes beyond mere moral principles in his exploration. His aim is to establish a universal understanding of ‘religion’, offering a well-defined definition and presenting a philosophical and theological doctrine. In this paper, we shall first delve into the foundations and underlying principles that shaped Aquinas’s interpretation of religion. Next, we will undertake a thorough examination of religion as a virtue, highlighting Aquinas’s emphasis on its intrinsic connection to justice rather than confining it to the realm of religious sentiment, piety, or devotion. Finally, our research will explore the specific terminologies employed by Aquinas to elucidate the concept of religion, providing a comprehensive and nuanced approach to the ongoing discourse on this topic. Aquinas’s contribution rests in his defence of religion’s inherent public nature, grounded in its anthropological foundation and its virtuous essence.

1. Introduction

Thomas Aquinas provides a definition of religion as the act of expressing worship and showing reverence to the divine (Super Sent., lib. 3 d. 9 q. 1 a. 1 d.), before he relates it to virtue. He portrays religion as rendering to God what is due to him (ST I-II, q. 60, a. 3.) and as fundamentally consisting of divine worship (CG lib. 3 cap. 130 n. 6). Aquinas approaches the entire question of religion from a methodological view that highlights a crucial initial point: all acts of religion, according to him, are human acts rather than mere acts of man, since they involve the rational faculties of intellect and will. This article seeks to investigate Aquinas’s understanding of religion as a contribution to the theological discourse on religion today. Consequently, the methodology followed in this work relies on an analysis of pertinent Thomistic texts dealing with this issue, so as to trace the development of Aquinas’s thought on this point. Religion encompasses two main aspects. It denotes the process of reconnecting with God through appropriate worship and entails a commitment to serve God in a distinct manner, through specific acts of charity and detachment from worldly pursuits. For our purposes, the term ‘religion’ will be used in this sense. The purpose of re-evaluating Aquinas’s definition of religion is specifically to comprehend his stance that stands in direct opposition to contemporary theories that tend to downplay the anthropological basis of religion, attributing it entirely to a primal and emotional instinct that is inherent in human beings. He questions the idea that religion predominantly originates from an intrinsic “sensation” that compels individuals to engage in specific behaviours. Alternatively, Aquinas affirms the rational nature of the human person, as well as the supernatural action of God who bestows grace on humans. What follows is an analysis of Aquinas’s essential writings on religion, encompassing both a broad and a specific perspective. Aquinas not only ropes in diverse religions but also investigates the universal concept of ‘religion’, offering a definition and presenting a philosophical and theological doctrine.

This paper proceeds in three steps. Initially, it endeavours to comprehend the underlying principles and contextual backdrop that shaped Aquinas’s interpretation of religion. On one hand, it draws upon the profound influences of Cicero and Augustine that laid the groundwork for Aquinas’s early comprehension of religion. On the other hand, it compares Aquinas with contemporary perspectives on religion, wherein a nuanced distinction is drawn between religio, pietas, and devotio. In the subsequent step, the paper embarks on an exploration of religion as a virtue (See Moncillo 1962; Centi 1967). By considering religio in its broadest sense, Aquinas asserts that religion possesses a public dimension. This assertion stems from the understanding that religion, by its inherent nature, outwardly and publicly manifests itself through acts of worship. Simultaneously, it also encompasses a spiritual dimension, often expressed through piety and devotion. Thus, this section delves into unravelling the essential characteristics that define religion. Finally, the research extends its focus to specific terminologies employed by Aquinas to elucidate the concept of religion. These include christiana religio, vera et falsa religio, and omnis religio. By delving into these terms, the study expands its scope and offers a comprehensive understanding of Aquinas’s nuanced approach to religion.

In conclusion, this paper duly emphasises the significance of Aquinas’s contributions to the definition and comprehension of religion. It refutes any reductionist tendencies that diminish religion to a mere religious sentiment. On the contrary, it upholds the inherent public nature of religion, drawing intricate connections between religion, morality, and justice (see Pizzorni 2001). Moreover, it sheds light on the cognitive and social dimensions of religion. By explicitly referencing religio in the key texts of Aquinas, a path is paved for the reader, empowering anyone to embark upon an exercise of comprehending Aquinas’s exploration of religion. In order to establish boundaries, this study will concentrate solely on the primary texts that directly address the topic of religion.

2. Foundations for Aquinas’s Interpretation of Religion

The phenomenon and concept of religion, existing before the very term that defines it, evoke a practice of outward rituals—an evolving expression of direct worship towards divinity, irrespective of whether it is within a monotheistic framework or otherwise. Its history has much older roots, and it was on these that Aquinas was able to draw to find a basis of support for his synthesis on this subject. In this ancient understanding, the emphasis is placed not on the subjective religious experiences or personal attitudes of individuals, but rather on the external observance of specific behavioural forms, ritualistic prayers, and adherence to prescribed precepts (Del Campo 1976). These points rebut the idea that theism emerged from deism, an idea having wide currency in the 17th century, seeking to establish a clear divide between natural religion and revealed religion.

In the early Christian centuries, a real qualitative leap was made in the way religion is conceived, not only from a theological but also from a philosophical point of view. The notion of religion moves decisively from the external level of a set of ritual rules to the sphere of knowledge of God. Synthetically, we could say that the notion of religion, which originated with the Greeks to indicate a set of rules of worship, evolved in the Roman world, with Cicero, to include the inner act of devotion, and discovered that it had to enter the sphere of knowledge. With the advantage of hindsight and adopting a Thomistic viewpoint, it becomes evident why such a step was necessary: one can only truly honour and love that which they begin to know, even if it is through comparisons and analogies (Agera 2000). The inner act of devotion, which decides the authenticity of religion in the subject performing the outward acts, presupposes some form of knowledge of God.

2.1. Aquinas’s Reading of Cicero and Augustine

The viewpoint regarding religion as the act of worshipping divinity was remarkably widespread in both ancient Greek and subsequent Roman civilisations (D’amecourt 1999). Plato, in his Laws, proposes legislation concerning religious observances, with the intention of regulating them through state institutions (Schofield 2016). While Aristotle does not directly engage with this subject, as his focus lies primarily on philosophical themes, his metaphysical ideas profoundly influence Aquinas’s theology and comprehensive apologetic theodicy (Segev 2017; McClymont 2010). Aristotle himself does not venture into the realm of prescribing ritualistic rules. Nevertheless, within the realm of antiquity, there were thinkers who, adopting a conception that could be seen as modern, such as Epicurus, regarded religion as an affliction of the soul arising from fear of the gods and the afterlife.

At the outset of his investigation into the complexities of religion, Aquinas, described as the most influential thinker of the medieval period (Wippel 1995, p. 36), sets out on a journey to unveil the rational underpinnings of this notion from a universal perspective predating the emergence of Christianity. Religion, Aquinas holds, embraces the complete essence of a person, extending beyond their sensory and emotional dimensions to actively involve their intellectual faculties. This signifies that engaging in religion necessitates a deliberate application of rationality. Rather than being confined to a specific non-Christian originator’s perspective, his pursuit aims to pave the path for religion’s manifestation throughout history, ultimately leading to its culmination. Remarkably, Aquinas finds his most authoritative source in Cicero, a philosopher and jurist, whose comprehensive vision of religion aligns with a universal definition. This harmonisation enables the correlation between religion and ‘natural law’, a benchmark we consider essential in establishing the fundamental criterion for validating the authenticity of religious belief.

The rich Roman legal tradition offers a cultural context that deeply influenced the formulation and refinement of religious concepts, including a comprehensive framework of regulations governing rituals and the responsibilities of religious practitioners. Within this historical context, two significant aspects of religion emerged. First, religion’s “social role” gained recognition as an indispensable component of state functioning. It served as a moral compass, guiding interpersonal relationships within civil society. Cicero’s De legibus extensively explores how states can attain divine favour and outlines the principles guiding the conduct and governance of favoured states (Cicero 2018; Beltrão da Rosa and Santangelo 2020). Second, the emphasis on “respect” and “reverence” towards the divine became increasingly prominent. This entailed acknowledging the transcendence of the gods and extending reverence, to a lesser extent, to revered historical figures and statesmen. Additionally, there was a growing emphasis on the internal dimension of religious practice, underscoring the importance of approaching the gods with genuine reverence and sincerity.1

Aquinas formulates a robust definition of religion by integrating Augustine’s work, specifically De vera religione, which deeply influenced Aquinas and provided a comprehensive exposition of his early Christian philosophy. This treatise aimed to convince Romanianus, Augustine’s primary student at Cassiciacum, to follow his example by transitioning from Manicheanism to what he deemed “the true religion”. Aquinas draws several significant insights from Augustine’s teachings on religion. Aquinas incorporates Augustine’s teachings on religion, emphasising the worship of the authentic God and the virtue of reverence. He also recognises the importance of the inner disposition of the heart in religious matters, which involves sincere devotion and alignment with God. Aquinas agrees with Augustine that religion serves as a unifying force in society, fostering shared moral principles and collective devotion to the divine. Additionally, he adopts Augustine’s view on the essential connection between faith and religion, where faith forms the foundation for genuine religious devotion and the proper honour of God (Roszak 2014). Finally, Aquinas holds great admiration for Augustine, who, despite the prevailing pagan, religious, cultural, and social customs within his community, endeavoured to direct people towards the path of true religion.

2.2. Contextualising Religion in Aquinas’s Writings

In this context, it is important to consider three interrelated terms employed by Aquinas and characteristic of medieval Europe (Swanson 1995): religio, pietas, and devotio. Aquinas particularly emphasises the significance of external displays of reverence as indicative of the soul’s disposition, as expressed through religio and devotio. The latter, devotio, in particular, receives extensive elaboration by Aquinas and becomes the primary term, while still recognising the essential role of the external dimension in religion (Berceville 1999a). Aquinas also devotes considerable attention to pietas but addresses it separately from the treatise on religion. This separation stems from the distinction between religion, which seeks to honour God through exclusive worship (latria), and pietas, which involves acts of reverent homage towards fellow human beings such as parents, relatives, and benefactors, or towards one’s homeland. Pietas should not assume the character of adoration to avoid degenerating into idolatry. Yet, with remarkable insight, Aquinas also establishes a connection between pietas and religio. He considers piety not merely as a moral virtue but as a “gift of the Holy Spirit” that crowns the divine virtue of religion. This perspective inspires one to worship and obey God not solely as the Creator and Lord of the universe, but as the heavenly Father. Through the gift of piety, Aquinas explains, one honours God Himself rather than an earthly parent (ST I-II, a.4).

According to Aquinas, the concept of “religion” should not be limited to multiple distinct “religions”, but rather approached primarily as a universal characterisation. However, Thomas lived in a historical period in Europe marked by challenges in the coexistence of diverse cultures and religions: Christians, Jews, Muslims, pagans, and various deviations from genuine religious practices. It is evident that Thomas, following the footsteps of Albertus Magnus, whose approach and methodology he seems to have adopted (Salas 2010), possessed a profound familiarity with the philosophies of eminent Jewish thinkers such as Moses Maimonides and Arabic scholars such as Averroes and Avicenna, among others (Buijs 2002). He frequently references their works throughout his own writings. Nonetheless, it is crucial to note that the scope of engagement with these thinkers was predominantly within the realm of philosophy rather than explicit theological or religious discourse.

This leads us to the discussion of contextualising religion in Aquinas’s writings. By placing religion among the virtues, it becomes evident that it can be seen as a component of justice (Nemec and Blaščíková 2023). There is a significant correlation between religion and law, indicating its inherent connection with natural law. The forthcoming section examines this particular aspect. It is essential to remember that for Aquinas, the foundations of morality always lie in anthropology and metaphysics (DeYoung et al. 2009). He also acknowledges the psychological and experiential nuances inherent in the modern understanding of the religious sense as explored by the philosophy of religions (Dewan 1981; Dougherty 1983). Additionally, he considers the cultural aspects associated with external cultic practices and the public manifestation of religion, as well as the more spiritual dimensions, such as the emphasis he places on ‘piety’ and ‘devotion’ (Berceville 1999b).

It must be clear, however, that Aquinas attributing religion primarily to sentiment is equivalent to depriving the act of religion of its essential components as a human act: the intellect and the will (Fiorentino 1997, p. 198). This is captured in Dougherty’s words:

“This is a key question for exploration, i.e., whether religion stems from non-rational forces in man or whether man’s intellectual equipment leads him to acknowledge a fundamental dependence on a transcendent being. [...] Those who deny a rational ground while still acknowledging the naturalness of religion, place the origins of religion in man’s emotional makeup. How one understands the emotions is of obvious importance. Do the emotions follow perception, or are they initiative of themselves? One’s theory of religion is in some sense contingent upon one’s theory of knowledge, imagination and emotion”

(Dougherty 2003, pp. 12–3)

Certainly, during Aquinas’s time, the problem was not posed in these terms that have emerged from the modern trajectory of philosophical and theological thought. Therefore, these reflections should not be interpreted solely as an exegesis of Thomist texts situated within their historical and cultural context. Rather, they should be considered in light of our present utilisation of the philosophical and theological principles that can be derived from them.

3. Religion as a Virtue

To gain a profound understanding of Aquinas’s exploration of religion, it is essential to situate it within the broader framework of “morality”,2 where he conceives of religion as a virtue (Staudt 2022). This perspective is rooted in the original theological-philosophical structure of exitus-reditus, which Aquinas employs throughout the Summa Theologiae. By aligning religion with the “cardinal virtue” of justice, Aquinas establishes a direct connection between them. In Secunda Secundæ, specifically from question 81 to question 100, Aquinas delves into the topic of religion extensively.

Aquinas develops his thought by distinguishing its principal interior acts, namely devotion (q. 82) and prayer (q. 83), and its secondary external acts of latria through bodily reverence (q. 84). He then proceeds to present another distinction between the offering of things to God such as sacrifices (q. 85), oblations and first-fruits (q. 86), tithes (q. 87), and vows (q. 88) and the taking of things from God, such as sacraments (see ST III) and the taking of His Name by adjuration (q. 90), in prayer (q. 83) or praise (q. 91), or in order to confirm an assertion (q. 89). He then refers to vices including superstition (q. 92), idolatry (q. 94), divinations (q. 95), observances (q. 96), and undue worship to the true God (q. 93), as well as the vice of irreligion, which is opposed by deficiency and includes temptation of God (q. 97), perjury (q. 98), sacrilege (q. 99), and simony (q. 100).

Aquinas follows in the footsteps of Marcus Tullius Cicero, who, in his work Rhetoric, classifies religion as speciem justitiae that is a particular manifestation of justice (III Sent, d. 9, q. 1, a. 1, sc. 1; Augustine, De Civ. Dei, XIX, 21). Aquinas refers to Cicero’s view, stating that “morals are determinable by law in so far as they pertain to justice, of which also religion is a part, as Tullius says” (I-II, q. 99, a. 5, ad 1).3 By adopting this approach, Aquinas emphasises religion’s direct connection to the rational dimension that governs one’s actions, particularly in relation to others, which is the primary concern of justice. Furthermore, by aligning religion with justice, Aquinas asserts that it cannot be conceived merely as a private and personal experience. Instead, it is an integral component of justice, which is governed by societal laws. In other words, religion is not separate from the legal framework but is intimately linked to the virtue of justice itself, which in its turn reveals inner intentions and attitudes. Ultimately, the correlation among religion, justice, and individuals’ inner disposition becomes evident.

Aquinas embarks on his exploration by questioning the validity of dividing justice (II-II, q. 57–122) into distinct “parts”. Having affirmed the appropriateness of such division, he draws an analogy between these parts and metaphysical divisions, which he posits as a basis for further analysis (See ST II-II, q. 61; III Sent d. 33, g. 3, a. 4). The chosen subdivision aligns with the customary scheme that categorises the components of a whole into subjective parts (subiectivae), integral parts (integrales), and potentials (potentiales).4 However, when applying this framework to the concept of religion, Aquinas introduces a necessary qualification. Since religion pertains to a noncorporeal “subject” while characterising a “human act” (voluntary act), the terms integrales and potentiales must be understood analogically and, thus, be preceded by the qualifier “almost”.

Aquinas employs this linguistic caution to encourage readers not to rush into definitive attributions, particularly in nuanced theological matters where the use of analogy is imperative. The exploration proceeds with a focus on the subjective parts, specifically distributive and commutative justice, which constitute the species of justice. Subsequently, Aquinas addresses the “quasi-integral” parts and the “quasi-potential” parts, including the virtues associated with justice (II-II, q. 61, pr.). Within this framework, Aquinas raises the question of whether there exist potential parts of justice and, affirming their presence, identifies religion as one of them. Thus, the concept of religion is situated within the third type of the justice subdivision.

Religion finds its place among the virtues associated with justice because of its essence of an act of “restitution” from humanity to God. Aquinas clarifies that this act is not driven by legal necessity but stems from a sense of integrity. He says, non ex necessitate legis, sed quadam honestate (III Sent, d. 33, q. 3, a. 4a sc). In the context of religion, it is not a compelled obligation but a grateful and freely chosen action, motivated from within. Aquinas highlights a challenge that arises in this context—the inherent impossibility of humans achieving a “perfect” restitution to God. He elucidates this challenge by pointing out two fundamental reasons. First, there exists an “infinite disproportion” between the giver (humankind) and the recipient of restitution (God). Second, the object of worship offered by humans to God cannot match the immeasurable value of what God has bestowed upon humanity (ST II-II, q. 80).

3.1. Aquinas Defining Religion

This section encompasses a review of texts by Aquinas that explore the theme of religion in its broader scope (religio in genere). This is examined from a ‘philosophical-anthropological’ point of view. The theological dimension will be more relevant from the point of view of religion in particular, where it expressly deals with the christiana religio (in Section 4). We must note that there is also no lack of important considerations of the cultural implications, especially in the passages where he is concerned to clarify the need, intrinsic to the concept of religion, for “external signs” of worship, for “visible” elements to manifest it, given the anthropological structure of humans, who know and express themselves through the senses with which their bodies are endowed.

As we shall see, in addition to the complete treatise on the virtue of religion in the Secunda Secundæ of the Summa Theologiae, numerous parallel passages are also found in other works, mainly Liber contra impugnantes Dei cultum et religionem, with which we shall start, and the Scriptum super libros Sententiarum (1252–1256), i.e., the commentary on the Sentences of Peter Lombard (especially in the third book). What follows is a consideration of Aquinas’s attempts to define religion and to explain the nature of religion in highlighting its essential characteristics.

In his work Liber contra impugnantes Dei cultum et religionem (Apology for the Religious Orders), Aquinas provides an early definition of religion that is rooted in its etymology (Contra imp, ps I). This is regarded as a polemical text written in 1256, serving as a defence of the Mendicant Orders against William of Saint-Amour’s De periculis novissimorum temporum. It should be noted that this work is not a systematic treatise in the traditional sense. Aquinas draws upon Augustine’s book De vera religione, where the term ‘religion’ is understood to derive from re-ligare, meaning “to re-bind”. Aquinas explains that the essence of religion lies in the reunion of every rational creature with God, to whom it was initially united before existing separately. This concept is captured in the verse “unto the place whence the rivers come, they return to flow again” (Eccl., 1). According to Augustine, religion serves the purpose of reuniting us with the one Almighty God. A similar sentiment is echoed in Scripture in the words “for from him and through him and to him” (Rom. 11:36).

Faith serves as the initial bond that unites humanity with God, enabling individuals to draw nearer to Him through their beliefs (Heb. 11:6). Aquinas explains that the fundamental duty of humankind in their earthly existence is to engage in latria, which is the act of worshipping God as the ultimate source of all things. This serves as a crucial third point in our study, emphasising that for a belief system to be considered a religion, it must have God as its intended recipient rather than any other being.

Consequently, the essence of religion lies primarily in latria, encompassing the sincere expression of true religion through various acts of worship. Augustine and Cicero both agree that religion involves the worship of God and is distinct from other forms of worship. Augustine emphasises this in De civitate Dei (Book 10), while Cicero defines religion as the observance of ceremonies and homage to the Divine Nature. Thus, the core elements of religion centre around genuine faith and the dedicated offering of latria to God. Aquinas further clarifies that religion also encompasses secondary aspects influenced by how people serve God. Quoting Augustine, Aquinas explains that worship extends beyond faith to include hope and charity. Consequently, acts of charity can be seen as meaningful expressions of religious devotion.

In his Scriptum super libros Sententiarum (Commentary on the Sentences of Peter Lombard), Aquinas provides an additional definition of religion. Drawing from Cicero, Aquinas explains that according to the conception of the author himself, religion is essentially worship. Cicero views religion as the performance of ceremonial worship directed towards a higher nature, commonly referred to as ‘divine’ (Super Sent., lib. 3 d. 9 q. 1 a. 1d sc). In another passage, Aquinas notes that religion involves the observance of ceremonial acts aimed at a higher nature believed to be divine. The term ‘religion’, as Isidore suggests, is derived from relegare, meaning to set aside something for God, while Augustine proposes it comes from reelect, signifying the act of choosing God once again after having lost Him (ST II-II, a.1, c.). Piety, on the other hand, refers to the diligent attitude of worship displayed towards parents, relatives, benefactors, and one’s country (Super Sent., lib. 3 d. 33 q. 3 a. 4 sc). Other concise definitions include statements such as “Religio est per quam redditur debitum Deo”, that is, ‘religion is the rendering to God of what is due to Him’ (ST I-II, q. 60 a. 3 co.) and “Religio enim in cultu divino consistit”, that is, ‘religion consists in divine worship’ (CG lib. 3 cap. 130 n. 6).5

This passage holds significance for our investigation from two distinct angles. First, it provides a concise summary, although not as comprehensive as Thomas’ other works, of the fundamental components of religion. These include the bond between God and humanity, which is reaffirmed through religious practices, the understanding of religion as an exclusive worship directed towards God in adoration, and the recognition of religion as an affirmation of faith. Second, what makes it intriguing from a modern standpoint is religion’s anthropological character offering believers the chance to grow in virtue. Aquinas aims to provide a broad definition of religion that encompasses its various facets, allowing for the inclusion of the secondary meaning associated with dedicating oneself to the service of God within the religious life of the new Mendicant Orders. While this particular aspect may not align with our present interests, the introductory premise establishing the character of religion in its broader sense, independent of its moral implications, is particularly noteworthy.

In the Contra Gentiles, Aquinas approaches religion by exploring its origin, portraying it as an innate inclination deeply ingrained within the rational human being. This inclination manifests as a reverential respect towards God, akin to an instinctive response. Aquinas further explains that religion is characterised as the worship of God, as it encompasses the acts through which humans bind themselves to God, ensuring that they remain connected to Him (CG lib. 3 cap. 119 n. 7). This connection stems from a natural sense of obligation, rooted in the recognition that God is the source of existence and the principle of all goodness. Within the realm of religion, Aquinas raises a series of questions that serve as the foundation for a comprehensive analysis of the religious dimension and its various expressions. These questions explore religion in its essence, its observable acts, and the vices that stand in opposition to it.

3.2. The Nature of Religion

Within the pages of the Summa Theologiae, one encounters a definition of religion that unveils its fundamental attributes. Question 81 in Secunda Secundæ is entirely dedicated to the essence of religion itself, wherein Aquinas addresses eight pivotal inquiries. These include contemplating whether religion solely concerns one’s relationship with God, whether religion qualifies as a virtue, whether it is a singular virtue, whether it holds a distinct character as a special virtue, whether it is classified as a theological virtue, whether it should be prioritised over other moral virtues, whether it encompasses external actions, and whether it is synonymous with holiness. The ensuing statements provide a profound insight into Aquinas’s comprehensive understanding of religion, shedding light on its fundamental essence.

First, religion relates directly and only to God. Relying on Cicero and Augustine, Aquinas explains that religion means re-establishing the lost bond with God. In other words, it means turning to God with one’s heart, choosing God anew after humans reject him (Augustine, De Civ. Dei, book X). Augustine plays on the words reeligere, i.e., to choose over again, and negligere, to neglect or despise. Or again, religion may be derived from religare (to bind together), wherefore Augustine says: “May religion bind us to the one Almighty God” (De Vera Relig. 55) and binding oneself again to the “one and all-powerful God” (Augustine, De Vera Relig.). Aquinas explains that religion, whether it is associated with the regular study of sacred texts, the persistent effort to reclaim what has been neglected, or its inherent quality as a binding force, fundamentally revolves around its connection to God. Aquinas explains that religion signifies humans’ profound link to God, who should serve as their unwavering bedrock, the ultimate objective guiding their unwavering decisions, and the One they forfeit when disregarded through sin. However, through faith and the genuine acknowledgment of their convictions, humans have the opportunity to restore that connection (ST II-II, q. 81, a. 1 c). Aquinas further elaborates that while worship is at the heart of religion, the service rendered is primarily directed towards God, but ultimately extends to one’s neighbour through acts of love. Only to God, in fact, is that act of submission (servitus) that is worship (latria). The act of directing worship towards anything other than God, specifically towards a created being, can be described as divine idolatry. These acts of love are a natural outcome of the virtues that accompany religion but are not proper to religion as such (ST II-II, q. 81, a. 1, ad 1). In short, ‘religion’ in relation to love of neighbour can be spoken of not in a proper sense but only in extenso nomine, or in the broad sense (ST II-II, q. 81, a. 1, ad 2).

Second, religion is a virtue. Aquinas references Augustine’s view that order, similar to mode and species, is connected to goodness (De Nat. Boni iii). Based on this, Aquinas argues that since religion entails the rightful honouring of God, it can be concluded that religion is indeed a virtue. Religion should not be seen only through the lens of justice but of a profoundly moral, interior, and even spiritual nature. Aquinas remarks that to show reverence to God is an expression of the gift of fear. Religion, on the other hand, involves performing specific actions out of reverence for God. Therefore, it can be understood that religion is not identical to the gift of fear but is connected to it in a higher sense. This is because the gifts (such as fear) are considered more excellent than the moral virtues (ST II-II, 9, 1 ad 3; I-II, 68, 8).

Third, religion is a single virtue. Aquinas addresses this matter to preserve the integrity of the virtue of religion, while also being mindful of its various emotional, psychological, or intellectual connotations. The argument supporting the distinctiveness of the virtue of religion draws upon the concept of virtue as a ‘habit’ (cf. ST I-II, q. 55) and Aquinas’s understanding of habits (ibid., q. 49–54), which explains how habits are differentiated based on their respective objects (ibid., q. 54, a. 2). Therefore, a single object can only correspond to a single habit. Considering that religion has a singular object, namely, the honouring of God as the source of creation and its governance, it logically follows that religion is unique in its nature.6

Fourth, religion is a special virtue. Aquinas clarifies that religion cannot be regarded as a mere subset of another virtue. While it shares certain similarities with another virtue, it does not align completely with it. This objection is dismissed because of the distinct manner in which religion is oriented towards its object, which is the good (bonum), based on its unique defining characteristic (ratio). Religion, in fact, is directed towards honouring God precisely because He is acknowledged as being “transcendent”. In the case of religion, its objective is to bestow appropriate honour upon God. As for God, He possesses a unique excellence since He surpasses all things infinitely and exceeds them in every conceivable way. Therefore, special honour is rightfully attributed to Him. Thus, it becomes evident that religion constitutes a distinct and specialised virtue.7

Fifth, religion is a moral virtue that is properly about things referred to the end. Based on tradition and Church doctrine, Aquinas concludes that the virtue of religion primarily pertains to the ‘natural’ or ‘rational’ aspect, which aligns it with the moral dimension. This distinction leaves faith, hope, and charity as the exclusive attributes of theological virtues. It should be noted, however, that this does not diminish the possibility of an infused dimension within the virtue of religion, as with other moral virtues. This infusion perfects and refines it, allowing for the introduction of the “seeds of the Word” (semina Verbi) referred to by the Magisterium, which ascribes a supernatural origin to them. Aquinas’s argument revolves around the differentiation between the ‘object’ (material) and the ‘end’ of a virtue, which enables the distinction between theological and moral virtues. A ‘theological’ virtue has God as its (material) ‘object’, while a ‘moral’ virtue has God as its ‘end’ or recipient. For instance, ‘faith’ centres on believing in God as the material object of belief (credere Deum), ‘hope’ focuses on anticipating the future enjoyment of God (fruire Deum), which is a challenging good to attain, and ‘charity’ directs love towards God (diligere Deum) as its object. On the other hand, ‘religion’ aims for God as the ‘end’ to which one aspires, as the recipient of acts of worship and the fulfilment of the debt owed to Him (sicut cum credimus Deo), rather than being directly focused on Him as the object (objectum).

Sixth, religion excels among the moral virtues. The virtues are deemed more elevated (meliores) as they draw nearer to their ultimate goal. Since God is the end of the moral virtues, it follows that the moral virtues become more elevated the closer they approach God. Among the moral virtues, religion stands as a virtue that comes closest to God. Hence, religion excels among the moral virtues because it is the one that most closely approaches the ultimate end of all virtues, which is God Himself (Walz 2019). Religion surpasses all other moral virtues in its proximity to God, as it engages in acts that are directly and immediately directed towards honouring the divine. Therefore, religion represents the highest form of honouring God, as it directly and excellently expresses devotion to Him (ST II-II, q. 81, a. 6 co). To be clear, however, this is not to consider religion as the highest of moral virtues.

Seventh, religion involves external acts. Humans offer honour and reverence to God not for His own sake, as He already possesses complete glory that no creature can augment, but for their own benefit. When humans revere and honour God, their minds willingly submit to Him, and it is in this submission that our minds find perfection. Just as the body achieves its full potential through the animating presence of the soul, and the air is illuminated by the radiance of the sun, our minds require guidance from the observable world to be united with God. As the Apostle Paul affirms, “invisible though they are, have been understood and seen through the things he has made” (Rom. 1:20). Therefore, natural knowledge prompted by the use of visible and tangible things in divine worship is eminently useful in bringing man towards union with God, but God is the one who does it, and He can do it in other ways. Consequently, the internal acts of religion take precedence and are fundamental to the very essence of religion, while the external acts are secondary and subservient to the internal acts.8

Eighth, religion is to be identified with holiness. In his analysis, Aquinas exhibits his expertise in discerning the dissimilarity between religion and holiness by analysing the etymology of the term “sanctity”. He elucidates that “sanctity” encompasses two separate connotations, namely, purity and the steadfastness associated with things safeguarded by law and regarded as inviolable. Furthermore, Aquinas establishes that religion and holiness share an inherent connection, although they differ logically rather than essentially. Religion and holiness are distinct in their expression, where religion manifests in external acts, while holiness primarily resides as an inner disposition that also predisposes one to embrace other virtues. Despite this difference in manifestation, holiness does not deviate from the essence of religion but is merely considered from a conceptual standpoint. Having addressed the broader concept of religion, this paper will now proceed to identify various terms employed by Aquinas to clarify the concept of religion.

4. Aquinas’s Specific Terms for Religion

Aquinas’s remarkable command of an extensive vocabulary within the realm of religion is truly awe inspiring. One notes, however, that he fails to delve into a treatise on religion(s) in particular, as he does when he explores religion in general necessitating external, visible, and public actions. For this reason, in this section, reference shall be made to precise terms that Aquinas intricately linked to religio, such as christiana religio, vera religio, falsa religio, and omnis religio, all of which will be thoroughly explored in this section. It is also worth noting that Aquinas employs a range of other terms when discussing religions beyond the scope of Christianity (See Von Balthasar 1987). These include judaeus, gentilis, paganus, infidelis, and mahumetista.

4.1. Expressions of Religion in Particular

The phrase christiana religio is one that Aquinas uses most in his writings, having a remarkable total of 59 instances. Of particular importance are the 10 occurrences in IV Sent, the 4 in Contra Gentiles, 1 in Summa Theologiae (I pars), 6 in II-II, 6 in III pars, 2 in Qaestiones quodlibetales I-IX, 6 in In Boethii De Trinitate, and 2 in De divinis nominibus. This term unmistakably denotes Christianity or Christian doctrine. Notably, we observe that the expression religio non christiana never appears within the same works, which may be of interest in the context of a discourse on religions (Dag 2019). Therefore, the term christiana is not explicitly utilised as a specific differentiating factor that classifies religions into Christian and non-Christian, thereby subjecting the latter to investigation. Rather, it serves as an equivalent to ‘true’ in the most comprehensive and perfect sense, aligning with the patristic and Augustinian tradition.

The subsequent term under scrutiny is vera religio, which emerges a total of 57 times, with 33 instances being direct citations from Augustine’s De vera religione. In the main works the expression vera religio appears 16 times with the following distribution: one reference in IV Sententiarum, 14 occurrences in Summa Theologiae: II-II, and once in III pars. In contrast, ‘falsa religio’ is mentioned twice, once directly and once indirectly in the Catena aurea, within a quotation from Augustine.9 Aquinas primarily employs the term vera religio to denote an “authentic religion” that possesses ontological truth and, secondarily, to describe a “religion with true content” or one that exhibits logical truth (see Adams 2019). From this perspective, Christianity shines forth as the true religion, embodying completeness and fullness, when compared to pre-Christian or non-Christian belief systems (See D’Costa 1995).

The final term to examine is omnis religio. Unlike the phrase vera religio, the expression omnis religio inherently acknowledges the existence of multiple religions, each of which shares certain characteristics that qualify it as a religion. Aquinas presents two assertions in this regard. First, he cites Augustine’s Contra Faustum, affirming that every religion possesses external signs (IV Sent, d. 1, q. 1, a. 2 sc). Just as in Christianity, where the Church acknowledges sacraments as signs, every religion incorporates outward signs. Second, every religion serves as a manifestation of some form of faith. Aquinas clarifies that faith is the fundamental requirement in religion, as every religion or worship of God represents an expression of belief in some capacity (IV Sent, d. 13, q. 2, a. 1 ad 4). Every religion is a manifestation of some form of faith (quaedam fidei protestatio).

4.2. Attributes of True Religion

A religion earns the designation of being ‘true’ when it aligns with the lex naturae, particularly by showing reverence to the one true God (monotheism) through authentic worship (O’Reilly 2013). Such worship encompasses both ‘external’ acts that are expressed through visible and public signs (such as the sanctification of feasts) and ‘internal’ acts like prayer and devotion. It appears that Thomas Aquinas acknowledged the existence of a religio that adheres to the lex naturae as having intrinsic salvific value. He recognised it as a form of faith (fides), stirred within individuals by the inner prompting of the Holy Spirit, thereby representing a certain degree (whether explicitly or implicitly) of fides mediatoris and, consequently, possessing salvific qualities.

In Aquinas’s Secunda Secundæ, several key attributes of true religion are emphasised. Foremost among them is the requirement for an authentic religion to be rooted in the principle of monotheism. Aquinas supports this notion through a sed contra statement, drawing on scriptural authority to assert that the term vera religio is synonymous with Christianity (ST II-II, q. 81, a. 3). Aquinas says, “On the contrary, it says in Eph 4, one God, one faith. But true religion affirms faith in one God. Hence religion is one virtue.” This quotation holds more weight as an authoritative pronouncement rather than an argument, serving to acknowledge a truth that extends beyond the realm of Judeo-Christian revelation and finds resonance in other traditions and rational theology. It implies that monotheistic religions encompass elements of truth, while other religions, at least in this particular aspect, are deemed false. Aquinas does not exclude that individual salvation—even of those who follow a polytheistic primitive religion—can be saved through extraordinary ways (independent of religious affiliation) that only God knows and enacts as He wills, as salvation by virtue of belonging to a religion.

Another essential aspect that distinguishes a true religion is the practice of daily prayer. Aquinas elucidates this concept in ST II-II, q. 92, a. 1, wherein he counters Cicero’s belief that those who engaged in daily prayer and sacrificial offerings for the safe return of their loved ones were engaging in superstitious behaviour, as documented by Isidore in his book of Etymologies. Aquinas asserts that the practice of daily prayer can indeed be a part of the worship within a true religion, challenging Cicero’s perspective.

Moreover, to qualify as true, a religion must offer exclusive worship to the true God. Within genuine religious practice, worship is directed solely towards the true God, and it is insufficient to worship any entity and assert it as true religion. Conversely, superstition leads worship astray towards unworthy recipients. Superstition is a vice that contradicts religion, not because it exceeds true religion in terms of intensity of worship, but because it directs worship towards inappropriate entities or utilises improper methods (II-II, q. 92, a. 1). Aquinas clarifies that ‘worship’ (latria) holds a dual meaning. First, it refers to the human act associated with divine worship. Second, ‘adoration’ can be understood as synonymous with religion. In this sense, considering it as a virtue [of religion], its definition dictates that worship should be reserved solely for those deserving of it (II-II, q. 94, a. 1 ad 2).

The Decalogue is another crucial component of true religion. This establishes a significant connection, like an “official seal”, between natural law and revelation (Levering 2008). The inclusion of the first commandment, which mandates the worship of a single God and prohibits idolatry, forges a link between the truth of religion and natural law (Smith 2020). In his respondeo, aimed at justifying the relevance of the first commandment of the Decalogue, Aquinas illustrates the rational necessity of true religion as an essential foundation for human conduct. This truth is revealed to reason through revelation, illuminating a content that reason is already capable of attaining on its own. It suggests that without true religion, the formulation of sound laws and the expectation of individuals adhering to them to foster harmonious civil coexistence becomes inconceivable. Without the underpinning of true religion, both individuals and society deteriorate, rendering the laws arbitrary and ineffective, and making the social fabric unbearable.

This leads Aquinas to speak of two distinct ways in which something can oppose true religion. The first way is through excess, wherein what rightfully belongs to religion is improperly bestowed upon something else. This pertains to the realm of superstition. The second way is through a deficiency in reverential regard, where God is despised. As previously discussed, this falls under the category of irreligiousness. Superstition hinders the practice of religion by diverting worship away from God. Aquinas explains that when one’s mind is occupied with improper forms of worship, it becomes impossible to offer proper worship to God simultaneously. A true God and a false god cannot coexist within the heart of a person. Furthermore, irreligiousness obstructs the honouring of God after having learned about Him. First and foremost, one must accept God in order to subsequently offer Him reverence. It is for this reason that the commandment prohibiting superstition is preceded by the one prohibiting irreligiousness (ST II-II, q. 122, a. 3 sc).

Having elucidated the opposing forces to the truth of religion, Aquinas proceeds to outline the essence of true religion in relation to natural law as embodied in the Decalogue. In essence, true religion can be defined as the sincere and genuine expression of reverence offered to the authentic God. Aquinas says, “The task of religion, in fact, is to give worship to God. And, just as in Scripture the divine realities are communicated to us through likenesses to corporeal things, so external worship is offered to God through some visible sign” (ST II-II, q. 122, a. 4 sc).

Aquinas then delves into the role of the Holy Spirit in the inner acts of religion, such as prayer and devotion. Notably, the term used to describe the Holy Spirit’s action is “instinct” (instinctu), highlighting the notion that in prayer and devotion, one is prompted more by an inward impulse from the Holy Spirit rather than a mere commandment. While the commandments of the Law primarily pertain to outward worship and tangible signs, the supernatural intervention of God becomes evident in the granting of grace, which motivates individuals to engage in acts that express a faith that is inherently supernatural, albeit not explicitly stated. These acts, in both instances, are attributed to the work of the “one” God, emanating from the Trinity towards creation as operations ad extra, and are ascribed to the Holy Spirit as acts of knowledge and love (Mullins 2022).

Within the realm of genuine religious practice, the meaningful utilisation of the aforementioned visible signs assumes immense significance. These signs encompass both tangible and material dimensions, serving a dual purpose: anthropological-cognitive and cultural-social. Anthropologically, human understanding progresses from the concrete to the abstract, with physical realities providing a pathway to apprehend spiritual truths. Culturally and socially, visible signs play a pivotal role in fostering recognition and solidarity among members of the same religious community, while also acting as distinctive markers that differentiate them from those outside the community. Aquinas establishes a connection between the theology of the sacraments and the concept of visible signs, wherein collective participation in a sacrament expresses a profound state of unity and communion, drawing inspiration from the teachings of Augustine (ST III, q. 61, a. 1 sc).10 Consequently, it can be inferred that in the realm of religion, corporeal, external, and clearly visible signs are indispensably necessary, and indeed, they are present. From this perspective, it can be argued that excessively spiritualist, introspective, and sentimental reductions render religion not truly complete, even from a purely anthropological standpoint (see Mailhiot 2017).

Another distinguishing characteristic of true religion is its relationship with Christ in the context of salvation. The salvific power of true religio derives from the fides mediatoris and is inseparable from Christ. However, for this connection to exist, there must be some link between true religio and fides mediatoris. A hint to this connection can be found in the statement that “faith is the first requirement for religion, as every religion or worship of God is a declaration (protestatio) of faith” (Super Sent., lib. 4 d. 13 q. 2 a. 1 ad 4).

In Thomas’ view, every religion, to some extent, represents a confession or proclamation of faith, and true religio, even before the advent of Christ, has the capacity to draw upon faith in the mediator to achieve salvation. This faith can be seen as more than implicit faith because it is closely intertwined with the adherence to true religio and is indirectly connected to Christ, albeit often unconsciously. It can be regarded as a form of faith that operates through the mediation of a true religio (which may not be Christian) without full awareness of its object (Christ), as true religion grasps only certain aspects of Christ without recognising Him as its source. The text of the fourth book of the Commentary on the Sentences contains an extremely important emphasis on the fact that salvation is, however it comes, always brought about by Christ and because of some form of relationship with Him. In addition, this suggests that no salvific value of a non-Christian religion, conceived independently of Jesus Christ, the only saviour, is conceivable (See Acts 4:12). There is one more element to try to explain the “way” in which the “connection” takes place between the one who is saved without knowing Christ and the salvation wrought by Christ. The term that appears decisive here for establishing the relationship with Christ who works salvation is fides. The logical passage, at least implicitly, is as follows: he who has come to know Christ (through the proclamation of the Gospel) is saved through ‘faith’ in Christ the mediator, but there is no other way of relating to Christ the mediator apart from ‘faith’, so even he who has not come to know Christ, if he is saved, can only be saved through ‘faith’ in Christ the mediator.

In conclusion, it is important to highlight that a religion presents certain doctrines to be accepted as true without requiring exhaustive proof, setting it apart from philosophy or science. The faith professed within institutional religion can surpass mere human belief and acquire salvific significance when it is implicitly linked to faith in Christ (Roszak 2018). Furthermore, this faith can unveil truths that surpass rationality and possess a supernatural nature, finding their ultimate fulfilment exclusively in Christian revelation (as seeds of the Word). Lastly, it is noteworthy to acknowledge the use of the superlative term verissima to describe the Christian religion, which is rooted in the faith of the Church. This implies a sense of completeness and progressive development that does not undermine the existence of partial truths in other religions (D’Costa 2009).

5. Conclusions

This article sought to undertake a meticulous exploration of Aquinas’s seminal texts pertaining to the realm of religion. Within these profound works, he reveals his indebtedness to two influential traditions: the Greco-Roman philosophical-legal lineage, with a notable influence from Cicero, and the profound teachings of the Christian tradition, in which Augustine’s profound influence looms large. What sets Aquinas apart is his all-encompassing approach that seamlessly weaves together philosophical and theological elements. Rather than confining his analysis to specific historical religions, Aquinas endeavours to formulate a universal understanding of religion by drawing upon a diverse array of existing definitions. While the focal point of the examined texts largely centres around the moral doctrine of virtues, particularly the concept of justice, Aquinas’s theory of religion transcends the realm of moral considerations. It emerges as a profound inquiry rooted in objective principles, driven by his unwavering dedication to establishing a comprehensive and enduring framework. The ensuing discourse will now highlight three pivotal insights stemming from the elucidated content thus far.

First, Aquinas’s early conception of religion centred around the profound act of expressing worship and demonstrating reverence towards the divine. Drawing from his influences and contemporary writings on God and religion, Aquinas emphasised the need for a clear distinction between religio and pietas. Religion, in its essence, pertained to the adoration of God, involving the exclusive offering of worship in a vertical dimension. This distinguished it from latria, which encompassed reverent acts directed towards fellow human beings in a horizontal dimension. During this stage of his thinking, Aquinas prioritises the direct communion with the divine, regardless of whether it occurred within a monotheistic framework or extended beyond it. Aquinas argues that outward acts in religion are crucial because they facilitate the acquisition of knowledge. According to him, our understanding begins with sensory experiences and gradually moves from the senses to the mind and intellect. Aquinas believes that visible signs play a vital role in comprehending spiritual realities, since the human mind requires tangible guidance to grasp invisible truths.

Second, in his study of Augustine, Aquinas delves deep into the essence of religion, seeking to comprehend its fundamental nature. According to Aquinas, religion can be understood as the reunification of every rational being with God, with whom they were originally joined before their individual existence. This marks a crucial step in Aquinas’s exploration of the concept of religion. Additionally, Aquinas appreciates the significance of the inner disposition of the heart when it comes to matters of faith. This inner disposition entails sincere devotion and alignment with God. Aquinas recognises the intrinsic connection between faith and religion, with faith serving as the foundational element for genuine religious devotion and the proper honour bestowed upon God. Consequently, Aquinas asserts that such collective devotion to the divine acts as a unifying force within society, promoting shared moral principles and fostering a sense of cohesion. Here, we refer to the social function of religion wherein the external signs and rituals of religion serve a social purpose by publicly manifesting religious affiliation, both within and outside the religious community. Aquinas’s comprehensive approach harmoniously integrates anthropological and theological aspects, emphasising the inner acts of devotion and prayer as the foundation of religion while recognising the functional role of external acts.

Lastly, religion, according to Aquinas, is intrinsically intertwined with faith, as he emphasises the vital significance of faith within the realm of religious practice. He emphasises the intrinsic connection between faith and genuine religious devotion, as well as the proper reverence towards God. In Aquinas’s view, faith serves as the foundational bond that unites humanity with the divine, representing a universal presence within all religions (Roszak and Huzarek 2019). Without faith, religion would cease to exist. Through the virtue of faith, individuals are able to approach God and engage in worship, recognising Him as the ultimate source and fulfilling their fundamental duty. Aquinas considers faith to be of utmost importance, as it directs human devotion exclusively towards God, distinguishing Him as the intended recipient above all other beings. Religion emerges as a central concept in Aquinas’s thoughts on virtues as it establishes and nurtures the bond between humans and God, as well as that among people themselves. Aquinas’s contribution rests in his defence of religion’s inherent public nature.