Starting in the early twentieth century, many Protestant theologians developed an allergy to metaphysics–that is, to the study of being as being. The allergy is, on many levels, understandable. For one thing, the conversionist and activist streaks within evangelicalism make metaphysics seem a dangerous distraction–we want to know how many souls we can fit in the lifeboat, not how many angels can dance on the head of a pin. For another, the old liberal Protestant tradition often made poor use of metaphysics–or at least, used metaphysics in a manner that was bad for the faith–so it made sense when evangelicals attempted a return to the pure Word of God over against metaphysical speculation. This metaphysical malaise has, however, left us marooned when faced with many of today’s thorny theological questions–questions on, say, the doctrine of God or ethics. The responses tend to be either capitulation to our prevailing culture’s metaphysical disinterest and rapidly shifting ethical mores (e.g. mainline churches) or circling the wagons to protect an ever-more incoherent biblicism which finds itself unable to address pressing questions for which it cannot find chapter-and-verse (e.g. evangelicalism, of which I am a part and on which this essay will focus). Of course, whatever happens, the Church in its esse will survive. But is there anything that can be done in the arena of metaphysics for its bene esse, and specifically in its evangelical quarters? Johannes Zachhuber’s magnificent new book The Rise of Christian Theology and the End of Ancient Metaphysics, in my reading, suggests so. It must be said at the outset that these concerns are not ones which Professor Zachhuber at all approaches in the work, but they are ones which it cannot help but illuminate. What, then, does he illuminate?
Zachhuber’s core contention is that, rather than merely rehashing pagan Greek thought, the post-Nicene Cappadocian Fathers Basil the Great (330–379), Gregory of Nyssa (c.335–c.395), and Gregory Nazianzen (329–389) forged a distinctly Christian philosophy from the crucible of the Trinitarian controversies following the first Council of Nicaea. Among other things, Zachhuber demonstrates that this Cappadocian philosophy, with its distinctive account of ousia and hypostasis, was, especially in the hands of Gregory of Nyssa, not just suited for questions of trinitarian theology, but for basically all areas of theology: “Gregory of Nyssa applied the same conceptual language [of ousia and hypostasis] to a range of other doctrinal topics including creation, salvation, and the eschatological resurrection and restoration of humankind. In this way Cappadocian philosophy permitted for the first time the systematic integration of many doctrinal topics into one systematic whole” (6). As such, Cappadocian philosophy became the Church’s theological lingua franca in the years after their deaths, such that Zachhuber can justly term it “the classical theory.” This classical theory has been seen as, in effect, a “theory of everything.” However, the philosophy was never applied to Christology, given that it was not a bone of theological contention while the classical theory was in development –“a fact that was to have grave consequences” (6). The question arises then: does a distinctly Christian “theory of everything” remain by the time Zachhuber’s narrative concludes?
We must follow the account to find out. By the time of the Christological debates of the fifth century (and following), the major shortcoming of the classical theory became evident: “[it] lacked a cogent explanation of the individuation of the universal. It was the application of the classical theory to Christology that made this flaw painfully obvious” (216). Although the Cappadocians had seen off the difficult puzzles of how three hypostases could fit with one ousia, their system was not ready to answer how one hypostasis could fit with two ousiai.
But so ensconced was the classical theory that both Chalcedonian diophysites and non-Chalcedonian miaphysites worked tirelessly to adapt it to underwrite their competing Christologies, but in diametrically opposed ways:
The miaphysites gestured towards a theory of particular nature. . . which recognized that the individual could also be called, and was, a physis. This served to underwrite their own claim that the Incarnate must have existed as one nature. The Chalcedonians, by contrast, tended towards a solution which distinguished an abstract placeholder of the nature in the individual from its carrier, the hypostatically existing individual.(217)
We do well to assume that all sides of the Christological debates recognized that, at some point, the mystery of the hypostatic union is precisely that–a mystery. Ultimately, we cannot answer the question “how can one hypostasis exist with two ousia?” (although some of the later thinkers Zachhuber engages do speculate on this to some degree). However, we can answer attendant questions—most significantly, “how does a single hypostasis exist with just one ousia?” The Cappacodians, it seems, lacked a cogent answer to this question.
So we must ask: after the rough examination to which the Christological debates subjected the classical theory, did any distinctly Christain “theory of everything” remain by the end of Late Antiquity? In time, tentatively, we might say yes. The bulk of Zachhuber’s book is taken up with a detailed study of the theological wrangling by thinkers both famed and obscure involved in reaching this point, but his narrative concludes with studies of Maximus the Confessor (c.580–662) and John of Damascus (c.675–749) as “the climax of Chalcedonian philosophy.” Although each theologian developed different answers to the question of how ousia and hypostasis relate, both denied that they exist in a zero-sum game, overturning an ancient philosophical settlement which always prioritized the one over the many. Maximus did so by making his primary metaphysical framework one of whole and parts (relating respectively to hypostasis and ousia) rather than universal and particular; John of Damascus did so by making hypostases rather than ousiai the carriers of being in which all else inheres, but which never themselves inhere (the Trinity excepted) (292), conceiving of hypostases in their individuality as instances of “historical non-repeatability” (301). Both theologians brought hypostasis, at last, out of the metaphysical shadows to share in the limelight with ousia.
Metaphysical Hope for Evangelicalism
What promise, then, does Zachhuber’s work have for the anemic metaphysics of evangelicalism? It may be this: if we comprehend that our Chalcedonian Christology arose from applying and adjusting the earlier classical “theory of everything” and, therefore, is not solely related to narrow theological questions, we can find within it an adjusted “theory of everything” and unlock metaphysical resources with which to address other areas of philosophy and theology. Baked into the Chalcedonian Christology which evangelicals still profess are wider philosophical commitments that can be put to use in other areas–philosophical commitments of which we need not be wary since we have already made them in our professions regarding the incarnation. Chalcedonian Christology, in other words, can be viewed as a Noah’s ark for the metaphysical wrangling which Zachhuber chronicles—and it is time for the passengers to disembark.
If there is anywhere that modern Reformed and evangelical churches retain some vestige of real metaphysical interest, it is regarding Trinity and Christology. Contemporary evangelical ordinands or Bible college graduates may not, by and large, be conversant in Platonic dialogues or Aristotle’s categories in the way that humanistically trained ministers were in the heyday of Reformed scholasticism. Yet they can almost certainly tell you that there’s a big difference between homoousios and homoiousios and that the miracle of the incarnation can be called a hypostatic union. Even if they are just shibboleths, shibboleths at least acknowledge that, like it or not, you’ve got to cross the Jordan somehow.
If Zachhuber’s point stands that the Cappadocian philosophy necessarily developed something like a metaphysical “theory of everything” in its (albeit incomplete) explication of ousia and hypostasis as it addressed the trinitarian controversies (a theory which was then successfully adapted throughout the course of the Christological controversies), then it stands to reason that, within their ongoing adherence to Chalcedonian statements regarding ousia and hypostasis, modern evangelicals have, necessarily, the tools they need to rebuild a broader metaphysics which will enable them to address (if not entirely answer) the most challenging questions before them about God and humanity. To put it another way: one can’t talk about the ousiai and hypostasis of Christ without ending up with things to say about ousia and hypostasis as such.
Retrieving Eternal Generation: An Example
We perhaps have reason to be optimistic that Chalcedonian Christology can be of use in this way within evangelicalism because Nicene trinitarianism has already done likewise by bringing about a recent retrieval of the doctrine of eternal generation. In the twentieth-century, evangelicalism largely jettisoned the key Athanasian doctrine of eternal generation. Scott Swain has noted that it would be hard to find a pre-eighteenth century theologian—Catholic, Orthodox, or Protestant—who would not affirm eternal generation; however, “a scan of recent evangelical systematic theologies and biblical commentaries reveals that evangelicals have not warmly embraced the aforementioned ecumenical consensus.” Wayne Grudem, whose 1994 Systematic Theology has been the go-to textbook on doctrine for at least two generations of evangelical pastors, has become a popular example of this cool reception of the doctrine. Grudem has described the doctrine as “having never been defined very clearly,” eschewing the term. James Dolezal describes Grudem’s position as a rejection of “the classical view that relations of origin (begetter, begotten, spirated) are sufficient to account for the real distinctions among the divine persons.” Such approaches to eternal generation and related doctrines (e.g. divine simplicity) are increasingly tied to a wider neglect of the “classical” Christian doctrine of God developed by Athanasius, the Cappadocians, and others, which has now generated a wave of retrieval theology seeking (although, some would argue with varying degrees of success) to reclaim what has been lost.
Despite this neglect of eternal generation however, evangelicals continued to confess the Nicene homoousion formula—a formula which is so effective that, in time, it has acted as a corrective, illuminating that it cannot actually be maintained without an accompanying confession of eternal generation. Following significant pushback during the so-called 2016 Trinity Debate (an intra-evangelical debate which I imagine, blessedly, Professor Zachhuber has avoided), the recent second edition of Grudem’s Systematic Theology presents a revised position affirming eternal generation and, in Fred Sanders’ reckoning, has “given his students the orientation they need to take their trinitarian theology further into the satisfying resources of the great tradition.” The metaphysical content of the homoousios formula is significant enough that, when its implications are abandoned, it can function as its own corrective.The metaphysical truth has emerged safely from Noah’s ark, and has now gone forth to multiply.
So much for the doctrine of God. But what about the other sphere in which evangelicalism has been caught so metaphysically flat-footed: human ethics? This question is perhaps more directly relevant to Professor Zachhuber’s core thesis: that the Christological debates of the fifth century and following precipitated an ontological and philosophical turn to the individual, in contrast to pre-Christian philosophy’s emphasis on the universal. Zachhuber is clear that it would be anachronistic to, for example, credit John of Damascus with birthing modern historical consciousness–yet it is highly arguable that his enquiries and those of other post-Chalcedonian thinkers rendered such questions feasible and intelligible (317). We must then ask: what ethical demands are placed upon us by a distinctly Christian understanding of human ousia and hypostasis?
This is, perhaps, the most metaphysically pressing ethical question of the moment in the West. I say “metaphysically” and “in the West”intentionally. Practically speaking, global issues which cost millions of lives such as the famine caused by war in Ukraine or the genocide of the Uighurs, are, in reality, the most pressing ethical issues of our time. Yet, typically, these are not regarded as posing unique metaphysical questions to us. Their evil is as apparent as solutions to them are apparently impossible. But the relationship between the self and human nature (if there is such a thing) is of the utmost relevance on the current frontiers of human ethics in an era of attempts to “transcend” human nature–whether in transhumanism or transgenderism.
The extremes of the “turn to the individual” have been outlined well by Carl Trueman in his recent book The Rise and Triumph of the Modern Self. Although he concedes he could easily have started earlier with, say, Descartes or Locke, Trueman starts his intellectual genealogy with Jean-Jacques Rousseau (1712–1778). Trueman, in fact, narrates something posterior to the turn to the individual: the inward turn, specifically the way in which “with Rousseau and then the Romantics, this inward turn plays out in a profoundly ethical manner and is used as the basis for a critique of the way society. . . forced individuals to conform to its conventions, to be untrue to their inner impulses, and therefore to be untrue to themselves and inauthentic.” This turn is accompanied by a turn “from mimesis to poiesis. If society/culture is merely a construct, and if nature possesses no intrinsic meaning or purpose, then what meaning there is must be created by human beings themselves. . . The social imaginary emerging in the nineteenth century was one that intuitively placed human beings as the sovereigns at the center of a universe to which they could give shape and significance.”
In other words, modern man is all hypostasis and no ousia. With the metaphysical category of human nature abolished, there remains no framework by which to deny the wholesale alteration and augmentation of the human body, and so we find ourselves in an age in which an individual hypostasis can on no grounds be opposed if it wishes to dramatically alter itself. Of course, Reformed evangelicals feel intuitively ill at ease with such innovations, but how are they to respond? Citing Genesis 1:27 is an excellent place to start, but evangelicals must be prepared to give an account for what underpins such a verse, and how we resolve the apparent tension in this very verse between the individual as made in God’s image and humanity as a whole.
We should also note that while we undoubtedly live in the age of the triumph of the modern self, there are also moments in modern Western life when we become blind to the unique wonder of a human hypostasis. The expressive individualism of postmodernism is regnant, but it can willingly muster mass dehumanization to its purpose when required, rhetorically reducing the vast swathes of deplorables to T.S. Eliot’s anonymous hollow men–“shape without form, shade without colour.” There are, strangely, moments when culturally conservative evangelicals feel called upon to defend the seemingly trite idea of human beings as preciously unique. These moments too require a metaphysical account.
If we turn to the ark of our professed Chalcedonian Christology, we may find that we have categories at hand to begin addressing such questions. This is precisely what Zachhuber’s account illuminates in such detail. The Church neither achieved nor maintained the Chalcedonian definition of Christ’s hypostasis and ousiai without an immense amount of intellectual legwork concerning hypostases and ousiai considered by themselves. And so, in the essential act of confessing our savior—human in every respect as we are—to be a single hypostasis, we can by good and necessary consequence affirm the unique and significant hypostatic status of any individual and ask what ethical demands this hypostasis places upon us. Yet we also confess that Christ exists in two ousiai, divine and human, and that he is, according to the Chalcedonian definition, “co-essential with the Father according to the Godhead, the Self-same co-essential with us according to the Manhood.” If he is co-essential with us, there must be a universal “essence” or “ousia” in which both he and we share—and so we must ask what ethical demands this shared ousia places upon us. Most crucially of all, we must ask how we act ethically without making the misstep, which Zachhuber chronicles time and time again, of giving one perennial carte blanche over the other. To briefly consider an example: belief in a shared, universal human ousia should strongly push us towards a rejection of the idea that basic elements of our embodied existence, such as sex or lifespan, should be cast aside or overriden by technological and medical intervention in the service of the desires of a particular hypostasis. And yet, this ousia is only ever encountered in these unique, individual hypostases which demand our recognition as such, and so, when we find one of these hypostases chafing against the reality of their own ousia, they demand of us a high level of attentiveness to the distinct circumstances which have led them to such a metaphysical conflict, so that we might act in such a way as to fully honor their metaphysical reality.
In tracing the development of the classical theory from the Cappadocians up to Maximus and the Damascene, Professor Zachhuber has demonstrated in the finest of detail that Christian theologians have already been wrestling for a long time with the apparent Mexican standoff between ousia and hypostasis and that it is not the case that one must always be marginalized at the expense of the other. In an age of deep ethical confusion, in which even those outside of the Church are casting about for ways of accounting for realities they intuit but cannot articulate, there seem few more worthy endeavors than the kind of metaphysical reflection made possible by this book. As it demonstrates, Christian theology has already seen off the metaphysics of the ancients. Perhaps it will soon do the same with that of the moderns.
Rhys Laverty is the Seior Editor of Ad Fontes and Managing Editor at The Davenant Press. His writing has been previously published by Ad Fontes, Mere Orthodoxy, and the Theopolis Institute.
 For a lengthier consideration of the way Zachhuber’s book illuminates the relationship between retaining orthodoxy and answer novel questions, see my colleague Joseph Minich’s essay in this symposium, “Philosophical Wonder and the Biography of Christian Theology”
 Scott R. Swain, “The Radiance of the Father’s Glory: Eternal Generation, the Divine Names, and Biblical Interpretation” in Retrieving Eternal Generation (ed. Fred Sanders and Scott R. Swain (Grand Rapids: Zondervan, 2017), 29.
 Wayne Grudem, Systematic Theology 1st ed. (Nottingham: Inter-Varsity Press, 1994), 245
 James Dolezal, All That is in God: Evangelical Theology and the Challenge of Christian Theism (Grand Rapids: Reformation Heritage Books, 2017), 133
 For some notable examples of such recent critiques, see Dolezal’s All That is in God, God of our Fathers: Classical Theism for the Contemporary Church (ed. Bradford Littlejohn; Moscow, ID: The Davenant Press, 2018), The Lord is One: Reclaiming Divine Simplicity (ed. Joseph Minich and Onsi A. Kamel; Moscow, ID: The Davenant Press, 2019), Simply God: Recovering the Classical Trinity by Peter Sanlon (Nottingham: Inter-Varsity Press, 2014), and Interpreting Scripture With The Great Tradition: Recovering the Genius of Premodern Exegesis by Craig A. Carter (Grand Rapids: Baker Academic, 2018)
 For a comprehensive chronology of this debate, see “The 2016 Trinity Debate: A Bibliography”, n.p. [cited June 15 2022]. Online: https://www.booksataglance.com/blog/thirteenth-updated-edition-trinity-debate-bibliography/
 Fred Sanders, “Adding Eternal Generation”,n.p. [cited June 15 2022]. Online: https://scriptoriumdaily.com/adding-eternal-generation/
 Carl R. Trueman, The Rise and Triumph of the Modern Self: Cultural Amnesia, Expressive Individualism, and the Road to Sexual Revolution (Wheaton: Crossway, 2020).
 Trueman, Rise and Triumph, 193.
 Trueman, Rise and Triumph, 194.
 Trueman, Rise and Triumph, 195-196.