“Something Perfect From Something Perfect”: The Dogmatic and Apologetic Functions of Divine Simplicity

I. Prologue: The Loss of Simplicity?

Christian theology has long regarded the attribute of simplicity as part and parcel with the classical understanding of God. However, divine simplicity has fallen out of favor since modernity, and the reasons for its rejection are still being rehearsed even until this very moment. In my Eastern-Asian-Indonesian context within the last few decades, there has been almost no new engagement or retrieval, perhaps to the point of neglect of the doctrine, as witnessed in some recent publications.¹ A more charitable analysis of such a lacuna could be because the concept of simplicity is too abstract and not directly relevant to the present contexts in the Eastern world, so many do not feel the need to mention or even defend the idea of a simple God. The well-known Christian philosopher-theologian Nicholas Wolterstorff once recounted his bewilderment of finding no mention of simplicity in John Calvin (most likely his Institutes) and thought probably Calvin “did not regard divine simplicity as a topic of burning importance for the life of the church in that boisterous refugee city which was Geneva.”² To be sure, this does not necessarily amount to a rejection of the doctrine, even when theologians of Calvin’s stature do not explicitly mention simplicity in their works.³ Perhaps, then, Christians today implicitly affirm simplicity without feeling the urgency to keep restating and defending it more intentionally. After all, as Ronald Nash once said, simplicity has “a public relations problem”— i.e., that it is difficult to explain the meaning to those without proper and deep theological training.⁴

Nevertheless, I suspect that these comments made in a recent theology textbook about simplicity are also representative of why many (evangelical) theologians in the East and West neglect the doctrine: “Most Christians have not even heard of the doctrine of divine simplicity.” And why is that so? It is most likely because simplicity “has no real biblical basis and has in fact worked to defeat the resources of a full-fledged trinitarianism.”⁵ In my estimation, such comments betray to us how many have failed to observe our catholic tradition since, as Richard Muller rightly states, “The doctrine of divine simplicity is among the normative assumptions of theology from the time of the church fathers, to the age of the great medieval scholastic systems, to the era of Reformation and post-Reformation theology, and indeed, on into the succeeding era of late orthodoxy and rationalism.”⁶ We somehow have not paid enough attention to able thinkers like Athenagoras, Irenaeus, Augustine, Gregory of Nyssa, and Thomas Aquinas, or even confessional documents like the Belgic Confession, the Augsburg Confession, the Westminster Confession of Faith, the Thirty-Nine Articles of Religion, among others. In other words, we somehow have forgotten the true meaning of the doctrine of divine simplicity and what it was for.⁷

This paper thus has a twofold aim, namely, to demonstrate why the doctrine of divine simplicity is indispensable to the Christian faith. First, I summarize how theologians across the centuries have used simplicity to ground and support these biblical doctrines, without which the Christian faith cannot be meaningfully defended: the Trinity, incarnation, and atonement. Second, I argue that we will lose so many opportunities to dialogue with our Muslim brothers and sisters if we reject simplicity, and I establish this by retrieving some of the ways in which the early Arab Christian theologians or apologists attempted to convince their Muslim interlocutors that the Christians do not worship three gods. In short, I attempt to show why we cannot afford to discard divine simplicity by explicating the dogmatic and apologetic functions of the doctrine. Lastly, I conclude with some reflections on the practicality and catholicity of the doctrine.

II. The Dogmatic Function: How Simplicity Changes Everything

There are many ways divine simplicity can be defined, but we can at least agree with Stephen Holmes that “to describe God as ‘simple’ means that God is ontologically basic. Any attribution of ontological complexity, any postulation of distinction or division into ontological parts, is excluded by this doctrine.”⁸ Many of the confessional documents that I mentioned above agree that it is essential to add to the clear biblical affirmation that “there is but one only, living, and true God” (Deut. 6:4; Isa. 44:6; 45:5) these descriptions about God: “infinite in being and perfection, a most pure spirit, invisible, without body, parts, or passions” (The Westminster Confession of Faith, 2.1; cf. Thirty-Nine Articles of Religion, 1). James Dolezal accurately explains the purpose of the doctrine:

This curious verbiage signifies the Westminster divines’ commitment to the simplicity that enables the Christian to meaningfully confess that God is most absolute in his existence and attributes. Adherents to this doctrine reason that if God were composed of parts in any sense, he would be dependent upon those parts for his very being, and thus the parts would be ontologically prior to him. If this were the case, he would not be most absolute, that is, wholly self-sufficient and the first principle of all other things. Thus, only if God is “without parts” can he be “most absolute.”⁹

Francis Turretin likewise explains why it is necessary to say that God is “perfectly simple” and “free from all composition” for the following reasons. If God is independent (a se), then he cannot be composite for whatever is composed is composed by another. If God is singular and absolute, then he can neither be divided nor composed for something would have to precede God and put his being in all its parts together. If God is truly perfect, then he cannot be composite again because it implies passive potency, dependency and mutability.¹⁰ Therefore, God “receives no perfection from another.”¹¹

This is why even critics like Alvin Plantinga say that the “sovereignty-aseity intuition” behind the doctrine “must be taken with real seriousness.”¹² This is because even when simplicity may not have a direct “proof text,” the doctrine is a consequence of the biblical affirmations that God is sovereign over all things and independent of all things (e.g., Exod. 3:14; 33:19; Acts 17:24-28; Rom. 9:15-23). In other words, rejecting simplicity means that the absolute sovereignty-aseity of God is questionable.¹³

Holmes suggests another reason why simplicity is important: “If we accept the linked scholastic account of God’s nature as dynamic, as pure act, then this doctrine means that God does one thing, and that is to be God – perfectly, eternally, and incomprehensibly.”¹⁴ Turretin agrees that simplicity can be deduced “from his activity, because God is a most pure act having no passive admixture and therefore rejecting all composition.”¹⁵ In the Bible, God is often described not just by abstract names—truth, righteousness, life, light, love, and wisdom, but also concretely regarding his actions—truthful, righteous, living, illuminating, loving, and wise (e.g., Jer. 10:10; 23:6; John 1:4–5, 9; 14:6; 1 Cor. 1:30; 1 John 1:5; 4:8, 16). All these references about God signify his simplicity which, as Adonis Vidu puts it, “qualify divine agency in a distinct way and differentiate it from any human agency.”¹⁶

In short, divine simplicity is affirmed throughout history to maintain a strict Creator-creature distinction in terms of their natures and actions or agencies. Although the concept itself seems to defy logic and irrational, it continues to have some tractions since the doctrine “allows” God to define logic for “he is the ground of all rules and Rule itself, and as such utterly unique.”¹⁷ Hence, in doing all kinds of theological tasks, all human epistemologies and ontologies must be disciplined by the confession that God is absolutely and perfectly simple.

III. The Oneness and Threeness of God

When the Westminster divines then continue to affirm the doctrine of the Trinity, we cannot but see that simplicity is presupposed: “In the unity of the Godhead there be three persons, of one substance, power, and eternity: God the Father, God the Son, and God the Holy Ghost” (WCF, 2.3). So Turretin, as he lists all the doctrines that almost all the Reformed orthodox agree to be counted among the so-called “fundamental articles of faith” that are essential to maintain Christian orthodoxy, it is not enough just to emphasize the Trinity but also the “unity of God.”¹⁸ As Herman Bavinck rightly stresses that “the oneness of God does not only consist in a unity of singularity . . . but also in a unity of simplicity.”¹⁹ It is no wonder, then, that Muller can claim that “from the time of the fathers onward, divine simplicity was understood as a support of the doctrine of the Trinity.”²⁰

It is interesting that in his Grassroots Asian Theology, the Singaporean Pentecostal theologian Simon Chan singles out the negative influence of Jürgen Moltmann’s well-known tritheistic model of the Trinity in modern theology as he discusses the convergences between the God of Islam and Christianity.²¹ It is likewise the case that, in the Indonesian context, the most well known academic theologian, Joas Adiprasetya, is heavily influenced by Moltmann.²² Like Moltmann, Adiprasetya makes much use of the concept perichoresis, including Moltmann’s panentheism in his most recent systematic theological work, Berteologi dalam Iman, as well as in his previously published dissertation, An Imaginative Glimpse.²³ Although I find that Adiprasetya is much more sympathetic to confess monotheism and the unity of God in his latest

work, I believe that more work needs to be done by supplying the concept of perichoresis with simplicity in order to safeguard trinitarian monotheism from tritheism.

Dolezal has rightly called into question, in my opinion, many recent attempts by evangelical theologians and (analytic) philosophers alike to construct the doctrine of the Trinity without simplicity, precisely because they think that the two are mutually exclusive.²⁴ Many then opt for what Dolezal calls “the compositional models of divine unity” or “social trinitarianism” which very much depends on the idea of perichoresis. Thus Moltmann: “The unity of the triunity lies in the eternal perichoresis of the Trinitarian persons. Interpreted perichoretically, the Trinitarian persons form their own unity by themselves in the circulation of the divine life.”²⁵ Nevertheless, Dolezal insists that “Without a sufficiently strong doctrine of simplicity, it becomes unclear why the three persons are not three gods (or three parts of the essence that are themselves less than wholly divine) and why the divine unity is not merely a moral and communal unity.”²⁶ Gavin Ortlund similarly finds that perichoresis alone is not enough:

The reason is that divine simplicity is able to bind the three persons, not merely into each other, but into the one divine essence. Strictly on the grounds of interpenetration, we are left further to explain why the interpenetration of the Father, the Son and the Spirit does not entail three interpenetrating gods. Why should the interpenetration of three persons yield one undivided unity, and not some complex aggregate? What is needed is not simply a mechanism by which to bring the divine persons into proximity with each other in the “circulation of the divine life,” but a mechanism by which to unite the divine persons as one. Where perichoresis may make oneness among the three persons possible, divine simplicity makes it necessary.²⁷

In other words, Ortlund does not argue that we should discard perichoresis from our understanding of the Trinity, but that even the prominent defender of perichoresis, John of Damascus, did not merely appeal to perichoresis but also divine simplicity to uphold trinitarian monotheism.²⁸ Augustine’s explanation is helpful here: “It is for this reason, then, that the nature of the Trinity is called simple, because it has not anything which it can lose, and because it is not one thing and its contents another, as a cup and the liquor, or a body and its color, or the air and the light or heat of it, or a mind and its wisdom.”²⁹ His point is again on the non-composite nature or essence of God, where the persons of God are not three separate parts yet somehow are united in perichoretic relations. Therefore, I agree with Scott Swain who says it rather bluntly,“There was and is no need for the doctrine of the Trinity if God is not simple, for there were and are plenty of sophisticated and unsophisticated ways of conceiving how three persons may compose one complex divine being or community.”³⁰

IV. The Communicatio Idiomatum and the Telos of the Incarnation

Theologians has also used divine simplicity to construe a fuller picture of the incarnation as part of the redemptive history. In the writings of the late fifth century theologian Pseudo-Dionysius, the unity-in-diversity of the simple God is used as the ground to show how the incarnation communicates something to us about the telos of creaturely redemption from fallenness. Pseudo Dionysius calls God “the principle of simplicity for those turning toward simplicity, point of unity for those made one.”³¹ Further, the one God in his “supernatural simplicity and indivisible unity” possess the “unifying power [by which] we are led to unity. We, in the diversity of what we are, are drawn together by it and led into a godlike oneness, into a unity reflecting God.”³² It is here that the incarnation of the Son is aimed toward redemption and to bridge the gap, so to speak, of creaturely complexity into divine simplicity (theosis): “the simplicity of Jesus became something complex, the timeless took on the duration of the temporal.”³³ We are reminded here of the famous quote by Athanasius: “He indeed assumed humanity that we might become God.”³⁴

But here the question regarding the final state of such a union can be asked: will we be truly become part of God or even become (one with) God? Again, Moltmann imagines such a state in these intriguing terms:

Once God finds his dwelling place in creation, creation loses its space outside God and attains to its place in God. Just as at the beginning the Creator made himself the living space for its creation, so at the end his new creation will be his living space. A mutual indwelling of the world in God and God in the world will come into being. The mutual indwellings then issue in a cosmic communicatio idiomatum, a communication of idioms, to use a scholastic phrase—that is to say, mutual participation in the attributes of the other.³⁵

Here we can see how the language of perichoresis coupled with the technical term “communication of idioms or attributes” are invoked to paint a picture of the eschatological state of God-world union. Moltmann is clearly on to something here, especially by invoking scriptural and scholastic languages. But is it the correct use of the communicatio, including what Scripture taught about our final states? If we are not careful like Moltmann (including other Lutheran theologians who teach that there can be a genus maiestaticum resulting from the communicatio), it is difficult not to fall into panentheism which construes the world in God and that there is indeed sharing of attributes between the two parties. But how does this not imply pantheism, where the distinction between God and creation is lost?

It is instructive, then, to see how Turretin explicates the doctrine of Christ’s two natures in relation to simplicity:

The Son of God is God-man (theanthrōpos) not by composition properly so-called, but by hypostatical union (by which the Word [logos] indeed assumed human nature in one hypostasis, but was not compounded with it as part with part; but stood to it in the relation of perfecter and sustainer to make perfect and sustain an essential adjunct, so that the human nature indeed did thence receive perfection, but nothing was added by it to the divine nature).³⁶

Similarly, Turretin incorporates the simplicity of the divine nature in the polemic against the Lutherans whether certain divine attributes (e.g., ubiquity, omniscience, omnipotence, etc.) are communicated to Christ’s humanity. His answer is no, since “either all the properties of the divine nature were communicated or none because they are inseparable and really one. Now of things which are really one, one being communicated, the other is necessarily communicated.”³⁷ In other words, “[God’s] simplicity hinders him also from being compounded with any created things so as to hold the relation of some part either of matter or form….This is so both because he is altogether diverse from creatures, and because he is immutable and incorruptible.”³⁸ Such an understanding of the communicatio should lead one to construe the God-world relation not panentheistically but in a different plane altogether. As Turretin explains Acts 17:28, a verse commonly understood as a support for panentheism, that “we are called the race and offspring of God…not by a participation of the same essence, but by similarity of likeness; efficiently not essentially.”³⁹ As I emphasized earlier, therefore, simplicity is important to maintain a strict Creator-creature distinction, while at the same time showing us how it can enrich our idea of the incarnation and redemption in Christ. Ortlund thus stresses that we cannot remove simplicity from our doctrine of God without some loss or damage to our understanding of redemption in Christ that has inspired the church’s worship and liturgy.⁴⁰

V. The Atonement and the Perfections of Divine Action

As noted previously, simplicity not only speaks to us about the divine nature, but it also makes a difference in how we talk about the divine action. As Vidu puts it, the doctrine “yields the following rule: in any divine action all divine attributes are present as its ground.”⁴¹ I think that is especially true as we come to understand the fuller picture of the atoning work of Christ.

Vidu has helpfully summarized some implications of the doctrine of simplicity to the atonement.⁴² First, divine simplicity means that we should not emphasize one divine attribute against another, as if there is a conflict between them. One popular understanding of the atonement is how there is a strife within God’s being, particularly in terms of his justice and mercy (cf. Hos. 11:8-9). Another is a way of understanding the concept of propitiation in Scripture (e.g., in Rom. 3:24-26) as the pagans do—that God somehow needs to be appeased from his boiling wrath. Another related view is the idea that the Father is wrathful toward the Son and that He must punish Jesus on the cross. These common views related to the atonement are misguided when we take divine simplicity into consideration. It is in fact impossible for God to have a conflict within himself, as if our problem then becomes his! It is also an overly anthropomorphic reading of texts that seem to indicate change from wrath to love in God, when there are other texts that indicate otherwise. And the language of the Father punishing the Son is inappropriate for the idea that God is simple stands behind the dictum “opera Trinitatis ad extra sunt indivisa” (the outer works of the Trinity are undivided). I. Howard Marshall’s comments are spot on: “There is an indissoluble unity between Father, Son, and Spirit in the work of redemption. The recognition that it is God the Son, that is to say quite simply God, who suffers and dies on the cross, settles the question finally. This is God himself bearing the consequences of sin, not the abuse of some cosmic child.”⁴³ This last part is also instructive, as it is a modern caricature to paint penal substitution as cosmic child abuse, precisely because they do not understand the language of divine accommodation or condescension in the Scriptures.⁴⁴ The point is, again, the doctrine of divine simplicity protects us from making those mistakes by giving us a better lens not to read the Bible literalistically.

Second, divine simplicity also implies that we cannot prioritize one model or theory of the atonement and pit it against the other. On the one hand, there is a tendency to accept all theories like recapitulation, satisfaction, penal substitution, moral influence, ransom, among others as equally valid and argue that no single theory can claim monopoly over the others.⁴⁵ On the other hand, there is a tendency to isolate one theory from another as if they are not connected at all. There is a case study in Indonesia where Joas Adiprasetya wrote a response to his colleague, Ioanes Rakhmat, who was outspoken about his liberal theology and had written a book just to overturn the penal substitutionary model of the atonement.⁴⁶ Part of Adiprasetya’s response was to say that if it is the case that Rakhmat is rejecting penal substitution, then it is no matter since there are other theories like Christus victor, moral influence, etc., that are available for Christians to uphold.⁴⁷ I think both tendencies can and need to be chastised by a firm understanding of God’s simplicity. As Adam Johnson writes, “The divine attribute(s) stand at the center of any theory of the atonement, shaping its constituent parts and determining its insights and limitations.”⁴⁸ So, regarding the first tendency, there are some good works that attempt to combine all theories together, but nonetheless without an adequate grounding with simplicity doctrine.⁴⁹ Regarding the second, I also do not think it is correct to accept that penal substitution, or other theories for that matter, to be overturned and move on as if nothing has happened, because even if it is just one theory, it has its place among the larger scheme of God’s redemptive work and it certainly has a role to display certain among the many attributes of God. But again, without simplicity doctrine, we have no reasonable ground to construe the atonement in such a way that perceives the various models as integrated to one another.⁵⁰

VI.The Apologetic Function: Our Common Yet Conflicting Ground with the Muslims

We now come to the second part of my argument that divine simplicity has been and can further be utilized for apologetic purposes.⁵¹ In his discussion about God in Asian contexts, Chan suggests that “a better case could be presented to the Muslim via a Thomistic conception of the Trinity.” He goes on to say how “Thomas’s concepts of God as ‘pure act’ (simple, perfect, without potentiality and change) and of divine ‘operations’ (such as ‘generation’ and ‘procession’) might serve as a better point of contact between the Muslim and the Christian.” According to Chan, it is because such an understanding of God “makes distinction in God conceivable without compromising the divine perfection and oneness.”⁵² I agree with his judgment and further demonstrates that his suggestions are indeed viable as we look back into how the medieval Arab Christian thinkers, namely Theodore Abū Qurra (c. 750–c. 830), Abū Rāʾiṭa Al-Takrītī (c. 755–c. 835), and ʿAmmār al-Baṣrī (d.c. 840) have engaged their Muslim counterparts as they responded to the objection that Christian understanding of the Trinity is absurd.⁵³

To begin with, it is important to summarize some of the apologetic steps that the three thinkers did have in common (though not necessarily explicit or in that precise order). The first step is to set up some common ground with the Muslims by arguing that Christians also believe in the one God—monotheism. They also seem to understand the Islamic understanding of God very well and can recognize some of the attributes they can agree with, even when they are quick to add that the two faiths understand “oneness” differently. The second step, which is the one in focus, is to make the move to argue for the Trinity through the simple essence or substance of God, especially by showing how the Muslims have tended to misunderstand what the doctrine of simplicity entails.⁵⁴ And the third step is they make frequent use of the tools from (Aristotelian) philosophy and categories to define terms and make distinctions. In this regard, they deploy everyday analogies in a careful and qualified way and with some anticipation that the Muslims will not easily accept them. In what follows, I focus more on Abū Rāʾiṭa’s structure of argumentation and supply it with the other two where appropriate.

For starters, Abū Rāʾiṭa establishes the monotheistic common ground by listing the Muslim conception of God’s attributes that are mentioned in the Qur’an and that Christians can likewise affirm:

…God is one, [who] has never and will never cease to be living (ḥayy), knowing (ʿālim), seeing (bashīr), hearing (samīʿ), without companion (lā sharīk lahu) in his substantial nature (jawhariyyatihi) or his dominion. He is the first and the last (al-awwal wa-l-akhir), the creator of the seen and the unseen, free from want, perfect [in] His essence, he cannot be described by those who [try to] describe him, elevated above imperfection and incapacity, not described by division (tabʿīḍ) nor partition (tajazzʾu), reigning, powerful, acting according to what He wishes, not seen, not felt, not comprehended and not limited, encompassing everything in His knowledge.⁵⁵

ʿAmmār similarly appeals to simplicity in warding off polytheism when speaking about the Triune God: “We have informed you earlier that He who created creatures with His Word and Spirit is without a doubt one in his substance and unique (munfarid) in His nature, division does not reach him, partition does not apply to Him.”⁵⁶ However, Abū Rāʾiṭa is quick to point out the crux of the Christian and Islamic difference in understanding the oneness of God. In response to the Muslims charges the Christians with worshipping three gods or that they confuse the one with the three, Abū Rāʾiṭa shows how the Muslims is misattributing the type of oneness that the Christians hold, namely “one in number” (al-ʿadad) instead of “one in substance” (jawhar): “We described Him as one perfect in substance not in number, because in number, that is to say hypostases, He is three; so indeed this description of Him is perfect in both aspects.”⁵⁷ We can see here that Abū Rāʾiṭa is using simplicity to say that it is wrong to construe the simple nature of God in terms of numbers. He elaborates:

With your description of Him by number, you describe him with divisions and imperfections. Do you not know that the individual ‘one’ in number is a part of the number? Since the perfection of the number is that which comprises all types of number. So the number ‘one’ is part of number and this is a contradiction of the words that He is “perfect” [and] “undivided.”⁵⁸

What Abū Rāʾiṭa is doing is forcing the Muslims to define what they mean when they charge that the Christian God is “three” instead of “one,” and using the doctrine of simplicity to the Christian’s advantage to establish the oneness of God in ousia even when God has three hypostases. In explaining that the oneness and threeness are not a numerical issue, both ʿAmmār and Abū Qurra make use of analogies to make this point. So asks ʿAmmār: “‘Does fire need its heat and dryness, and does water need its coldness and moistness?’…you know that the natural constitution (sūs) of the substance of fire is heat and dryness, and the natural constitution of the substance of the water is its coldness and moistness.”⁵⁹ ʿAmmār’s point is that although one can distinguish between the fire, its heat and dryness, or the water, its coldness and moistness, one would not refer to it as three fires or three waters. Similarly, Abū Qurra:

We are not of the opinion that the heat is more related to the fire than the Son is related to the Father nor that the heat is more connected to the fire than the Son is to the Father, and each one of them [Father and Son] is a hypostasis, because the divine nature does not accept composition as bodies do. Nor is there matter and form in them [the hypostases] and one does not find difference (ghayriyya) in a certain hypostasis from among them. But the position of the Son [in relation to] the Father is the same as the position of the heat of the fire [in relation to] the fire and the ray to the sun and the word to the mind, though the Son is a complete hypostasis, because the divine nature is too refined to have difference in terms of its hypostases.⁶⁰

Again, the takeaway is not that the simple nature of God is like that of fire, water, the sun, or the mind; rather it is the indivisibility or inseparability of the various aspects within those entities that helps us to establish the necessity of the one simple God with three eternally subsisting persons.

Abū Rāʾiṭa goes further to elucidate how the aforementioned divine attributes are related within God’s substance or essence by delineating these possibilities: “[1] either as entities other than Himself, ‘as one partner is related to another’; [2] ‘from Him,’ as an action He has made; or [3] ‘from His substance.’”⁶¹ The first two are obviously unacceptable for the Muslims (and the Christians), leaving the third with two further possibilities: “[3.1] either they are ‘parts of something perfect,’ which neither party can accept as this allows division in the Godhead, leaving the only other option…that these attributes are [3.2] ‘something perfect from something perfect.’”⁶² Through this process of analysis and elimination, Abū Rāʾiṭa then sets up the stage to argue for the Trinity, particularly the Christian understanding of eternal generation and the deity of the “two hands” of God (Word and Spirit), by establishing what the Muslims and the Christians would want to affirm regarding divine simplicity.⁶³

We could go further in analyzing how the three Arab Christian thinkers establish the doctrine of the Trinity and respond to the Muslim objections, but my point here is clear: they all appeal to divine simplicity as the doctrine that serves as the common yet conflicting ground with Muslims. Without some understanding of the doctrine, it would be difficult for Christians to help Muslims grasp why the triunity of God does not amount to positing three gods. Even when the two faiths clearly have different conceptions of God and his simple nature, there are great similarities and the two are much closer to one another compared to other non- or pantheistic religions.⁶⁴

VI. Concluding Reflections

I have attempted to show why the doctrine of divine simplicity is essentially valuable not just to secure biblical and rigorous accounts of the Christian doctrines of the Trinity, incarnation, and atonement, but how it can provide opportunities to dialogue with, including perhaps to evangelize the Muslims who likewise affirm simplicity yet reject the Trinity. By demonstrating the dogmatic and apologetic functions of the doctrine as I have done here, I hope to stimulate further thinking at least in two areas. First, it is important for pastor-theologians in any context to be able to provide explanations as to why any doctrine is indispensable by precisely showing the implications of one’s rejection of it. A common and well-spread posture of Christians in the East is that doctrine has no practical relevance whatsoever for daily living.⁶⁵ Such a posture will remain, I am afraid, if we continue to talk about theology or doctrine in an abstract and theoretical way (not that I think it has no place to do so or that its mysterious elements must always be explained away). Second, it is instructive for pastor-theologians in any context to master historical theology and continue to retrieve it for the sake of the contemporary church. As I intimated earlier, the loss of divine simplicity in the contemporary scene is most likely due to unfamiliarity with the catholic teaching on the Trinity. By familiarizing ourselves with how theologians across the centuries have taught simplicity, we can minimize errors while continuing to profess our reasonable faith as we witness the beauty of the perfectly simple Triune God of the Gospel.