Katherine Sonderegger freely admits that in her Systematic Theology, Volume 2 she has written “an unfamiliar, perhaps odd book on the Holy Trinity” (p. xxix). It is also a masterpiece, a sustained virtuoso performance at the highest level of academic systematic theology. Sonderegger attempts things that only a handful of living practitioners could aspire to; she sets for herself lofty goals and then conjures creative strategies for pursuing them. Since the publication of the first volume in 2015, I have recognized that Sonderegger’s books demand to be read twice: a first time admiringly, with sheer gratitude that such a voice is speaking in this generation, and a second time for critical response to the “unfamiliar, perhaps odd” things she proposes.

The first reading corresponds to Sonderegger’s authorial graciousness, as she celebrates a wide range of interlocutors, praising wherever she can, and seeking to synthesize all partial truths into a more comprehensive vision. It sometimes seems as if nobody is really quite wrong, on Sonderegger’s account—not even Tillich! But the required second reading corresponds to her iron determination that all is not well in the realm of modern trinitarian theology; she sees much disarray; many things need to be decisively re-oriented. She has taken sides, and responsible readers have to give an account of where they stand in this new landscape.

Fortress Press, 2020

In broad strokes, here are the problems Sonderegger sees in modern trinitarianism: It treats the Old Testament as a merely incipient phase in progressive revelation, where the Trinity is not yet to be found. It treats the revelation of the Trinity as so immediately bound to the history of salvation that the missions of the incarnate Son and the Pentecostal Spirit are the only clues to processions in the life of God. It approaches the Trinity as a truth purely revealed but otherwise unknowable, and therefore only intellectually credible in a double-negative sense (not not credible). In its most fervent phases, modern trinitarianism is alarmingly prone to collapsing the being of God into the history of salvation without remainder. It has few defenses against mutating into hard, social trinitarianism, resulting in a view of God as a group of three divine people closely linked and actively cooperating. Overall, trinitarian theology has devolved into an indoor sport in a club limited to Christian membership, very important for insiders but dwindling into insignificance a few feet out from the front door. This is a composite sketch which combines unlike features, and probably doesn’t match any actual single theologian. Readers who recognize some of these features in conventional trinitarian theology may still disagree about whether they are problems or solutions. But the sketch shows what Sonderegger is setting out to correct.

Sonderegger administers correction only incidentally by way of critique, but preferably by way of massive, constructive counter-proposal. Here is what Sonderegger counter-proposes: The immanent Trinity of God is manifest in the altar sacrifice of the Old Testament. This manifestation is discerned by a contemplative or metaphysical reading of Scripture, one which takes the Bible’s genre and idiom as disclosures of ultimate reality. In my view, this is the pons asinorum for grasping Sonderegger’s proposal. A more conventional approach to discerning the triune being of God in the Old Testament would be to treat Israel’s altar sacrifice as a kind of Old Testament mission of the Son and/or the Spirit. But Sonderegger pursues no such path. We get to the heart of what she is doing in this volume when we recognize that she finds the triune LordIf the God of the Bible is really triune all the way down and all the way back, then that triunity must be present also without reference to the salvation of humans, and without reference to revelation to humans.
in his holy temple before and apart from any revelatory or redemptive missions of the Son and the Spirit—not just historically earlier than the missions of incarnation and Pentecost, but more radically, at a level that is both epistemically and ontically prior to any missions whatsoever. “Not all is soteriology,” this volume systematically exhorts us, and “not all is revelation.” If the God of the Bible is really triune all the way down and all the way back, then that triunity must be present also without reference to the salvation of humans, and without reference to revelation to humans. This is why Sonderegger links triunity to holiness, and especially to aseity.

Sonderegger argues that there is processional divine life manifest in fiery sacrifice, without any divine sending making it manifest. In fact, in an important sense that takes some time to sink in, the manifestation of the processional life of God in Israel’s sacrifice is even more primal than its terminus in trinitarian persons. In classic trinitarian theology, it is the mission of any trinitarian person that presupposes a procession; but Sonderegger’s argument turns on the insistence that the mission of a person of the Trinity is not the only way for a worshiper to come into the presence of the Trinity’s processional life. “We can discover and learn of, learn from, and feed on, the Triune Being of God in the Old and New Testaments” (p. 239). Trinitarian aseity means that God would live by internal processions even if there were no missions appended to them by grace. So far so good (and I’m tempted to say something risible like “Thomas Aquinas and I agree”). I think Sonderegger goes further by claiming that the processions are knowable in the Old Testament. If not processions, at least processionality, or Procession capitalized. It’s a bold hypothesis with wide implications for the structure of trinitarian theology: What if the doctrine of the immanent Trinity is an Old Testament doctrine about God’s being, while the economic Trinity is a New Testament doctrine about God’s gracious action? Even though I do not find the thought project supportable in face of the evidence, or preferable to a more traditional schema that finds essential unity taught clearly in the Old Testament and personal distinction revealed in the New, nevertheless it is a stimulating prompt. As Matthew Levering says in his commendation of this volume, its proposals “awaken us all from the Trinitarian slumbers, especially those of us who thought we hadn’t dozed off.”

How does all this work together in Sonderegger? I think I can expound it most clearly by working in a reverse order from her own exposition. So, with spoiler alerts in place (and this is a uniquely suspenseful book of theology!), I’ll begin at the end of the volume, providing a little more detail on what is manifested of the processional life of God in sacrifice, and then backing out to see how this gives Sonderegger’s treatise on the Trinity its peculiar shape.In a longer review, I would then give attention to the underlying account of Scripture that supports this unusual trinitarian theology, but I think and hope that other participants in this symposium are better equipped to consider that, so I will leave it alone.

Triune Holiness in the Temple

The God of the Bible is in himself holy fire. In fact, there is in the eternal life of God a kind of perpetual self-giving and self-receiving that we can contemplate under the image of a self-contained fire. The divine fire doesn’t simply blaze forth and expend itself into the surrounding atmosphere (as if there were a surrounding atmosphere into which God might disperse), but has a perpetual structure of blazing forth within a particular, concrete form as it returns to itself. The phenomenology of fire, visual and otherwise, is so significant for Sonderegger that this book should probably be read by a fireplace: the paradoxical play of flame that is constantly rushing upward rapidly and yet standing there in the hearth as a bright object, not going away. It matters to Sonderegger that the divine fire is not simply a “pulsing” or “an Energetic Bundle that merely radiates or diffuses,” but is rather a power that reaches its own finality within itself.The God of the Bible is in himself holy fire. The fire that is God terminates internally in its own perfection, that is, in the divine persons as finalities.

When God is present at the altar, Sonderegger says, “Israel’s temple sacrifices manifest and correspond to the Triune Lord’s Self-Offering, His costly descent and ascent as Gift.” That is, “the Levitical account of sacrifice reinscribes the Processional Life of God” (p. 367). The task she sets herself is “to think trinity, to think the Generative and Holy Life of the One God, as it is exemplified, manifested, and taught under the act and idiom of sacrifice” (p. 395).

Perhaps here we see why the fiery sacrifice cannot be a divine mission, but must be a theophany. The life of God is manifest on the altar, but what can be seen there is not a life of processions-behind-missions. Missions are unique historical events; they can be dated, they mark points of progress in an unfolding divine plan, they move salvation history along. But the altar sacrifice is something different: it is not primarily instruction or historical deliverance at all, but presence and manifestation. Sonderegger is very careful with her language in this context, perhaps because she is working to avoid falling under the compulsive logic of a doctrine of revelation—especially as modern theology has understood revelation, as solving some notorious epistemological problems from Königsberg. What happens on the altar is not a mission but a work, and “these mighty workings of the Spirit are marks of the Divine Life that carry the eternal with them. They are a permanent hallowing” (p. 373). On the other hand, what is seen there is more than an action, and Sonderegger’s avowed aim is “to distinguish—not separate—the Manifestation of the Living God in Israel from the Divine Workings ad extra” (p. 374). The sacrifice at the altar is theophany to Israel, and in that way it is “the manifestation of the Concrete Life of God, the Generative, Spiritual Life of the Tri-Personed God, visiting His people” (p. 373). The important point to notice here is not that the sacrifice happened at some point in history, or at multiple points throughout history, but that it happens in the Bible, in Exodus and Leviticus and so on: it is as the word of God in Holy Scripture that the sacrifice is a manifestation of God’s self-hallowing. “In virtue of the Divine Processive Life, Israel’s history, from tabernacle to Second Temple, is a record that abides, that never recedes into the barren and fixed past. It is eternally animated by the Divine Life. We can say it simply: It is sanctified, consecrated” (p. 373).

It is tempting for the reader (at least this reader) to try to fit this processional life of God into more conventional trinitarian patterns, to identify three discrete elements of the fiery sacrifice that map satisfyingly onto three persons of the Trinity. But I think Sonderegger frustrates this attempt intentionally, partly by keeping the beats down to two whenever possible, and partly by unfolding a plethora of alternative triads that are all equally plausible. So at one moment “the Holy Fire of God and Its Glory are the Old Testament expression of the Trinitarian Processions” (p. 412), which would seem to give us names for the Son and Spirit in sacrificial idiom: Fire of God and Glory of that Fire. Just a few pages later we get a possible naming of the first person, when we are told that “the Rupture and Descent, the Outpouring and the Offering that is the Processional Life of God, has an Origin . . . and this source is not the Nature Itself. It is the Majestic Reserve and Primacy of the Father” (p. 416). Or again, more elaborately, “what is offered in the Holy Descent is the Divine Self, Eternally the Offered; the smoky ash returned in good pleasure to the Origin is the Gift, Consummated, Perfect, and Whole—Holy” (p. 418). I think here the Father is to be discerned in the Self or the Origin, the Son in the Offered or the Gift, and the Spirit in the cluster of concepts that together mark the consummation of the whole.Sonderegger already elaborated on the Spirit as the return, acceptance, or completion of the fiery transaction in her first volume; what she says here depends on that. But the correspondences slip and slide into each other and, crucially, glow back into the one reality that is the processional structure of deity itself: “God’s inner Life. The Lord God just is Holy Fire” (p. 413).

The Priority of Procession(s)

If Sonderegger makes it hard for us to count to three in this fire, it is not because she intends to burn away the three persons of the Trinity: they are definitely here, and she promises they will feature in the forthcoming volumes’ accounts of mission.Not all is Christology, but she promises Christology! Instead, her goal is to keep our patterns of thought about the God of the entire Bible from settling into a “holy triangle” or succumbing to a “habitual reversion to lists” (p. 442). Strong reversion to the one divine life is of course a helpful motif in reaching the goal of this instruction: to present trinitarianism as a form of monotheism. But any monotheism that is biblical is a recognition of the living God, and to confess that God is living is to stand before the processional life of God. “The Processions . . . Procession in the singular does a lot of work for Sonderegger’s trinitarian theology: it is the “Engine of Unity.”structure and define Deity Itself, God’s inner Life. The Lord God just is Holy Fire” (p. 413). We might say that if some ways of teaching the Trinity draw our minds to unfold out toward triangles and lists and the clearly distinguished three persons, an alternative way of teaching the Trinity would draw our minds to enfold in from the three persons back to the two processions, and finally to the one processional life of God.

Tracing such a movement into the divine unity helps name some of what Sonderegger is doing. Her partial alignment with Thomas Aquinas’s treatise on the Trinity in the Summa Theologiae is instructive: Thomas’s first Question on the Trinity begins with an article asking “whether there is procession in God,” and affirming that there is (ST 1:27, article 1). But in the next four articles, Thomas explores the duality of divine procession, distinguishes the two, relates them to each other, and denies that there are more than, or less than, two. Sonderegger seems to deny this.In section 5.3, on the unicity of the processions; pp. 420–459. Procession in the singular does a lot of work for Sonderegger’s trinitarian theology: it is the “Engine of Unity” (p. 457). Procession in the plural, however, does not seem to have a true place.

This is, I think, the most obviously revisionist moment in an unusual book. It is the point where Sonderegger shows her deep knowledge of the classical trinitarian tradition, gives her reasons for dissenting from it, and claims that she stands here because she can do no other: “We have not properly heard the idiom and witness of Holy Scripture if we insist on two distinct Processions” (p. 429). Speaking for myself, I dissent from Sonderegger’s dissent, but having said so, I want to move briskly along to indicate the goal Sonderegger is pursuing throughout this very demanding part of her book. For complex reasons into which we cannot look very deeply here, Sonderegger sees in the Holy Spirit the fullest expression of the processional life of God. It is more traditional for the eternal generation of the Son to take center stage as “the fulcrum of the divine life” (p. 432), so that many large-scale arguments can take the form, “the Son is from the Father, and so also is the Spirit, in this different way.” Sonderegger points out that the Spirit’s procession is more clearly processional. As a result, she can make arguments that take the form of confessing the Spirit and then including the Son: “The Processional Act is principally and most specifically Spirit; It also is Son, Son of the Father” (p. 457).

Sonderegger closes the loop in this strangest part of her argument by reverting to the fiery idiom for the processional life of God: “The Nature proceeds. That is what it means to say that God is Fire” (p. 441). God’s holiness is the eternal self-hallowing of the triune Lord; “the Triune Lord generates Holiness; this is the Self-Sanctification of God” (p. 473).With these metaphysical words, inevitably capitalized, Sonderegger turns her demanding work in trinitarian theology toward a plain, pastoral application. What is manifest in fiery sacrifice in the life of Israel is the eternal fiery nature of God, a processional life in which he blazes forth with holiness and love. This blazing forth within is “the consecration, the hallowing of Being Itself” (p. 474).

And with these metaphysical words, inevitably capitalized, Sonderegger turns her demanding work in trinitarian theology toward a plain, pastoral application. It is an application that offers strong encouragement to many people in many situations, but seems especially poignant in the isolation and disruption of the current pandemic, with the discouragement and depression it brings in its train. The almighty holiness of God, grasped in its processional dynamic as God’s permanent self-hallowing, is an energetic rejection of retreat from the world as a place of goodness. It preempts existential nausea. “The dogma of Trinity just is the intellectual affirmation that Being is Holy,” Sonderegger tells us (p. 475). This statement goes deeper than anthropology, deeper than cosmology, reaching down all the way to the foundations of ontology: “not simply an affirmation that the creation is good. It is that, certainly, but it is also far more” (p. 475). To see the processional life of God in the Scriptures of Israel is to see that “in all Eternity, God is enacting the Structure of Being,” (p. 476) and that structure is Trinity.

Sonderegger’s account of the Trinity is disorienting. I confess that it seems conceptually upside down and hermeneutically backward in many ways. It could hardly look otherwise to a theologian who, like me, has labored for some time at the task of tracing the alignment between the Trinity and the gospel. There are many ways of policing the boundary between divine aseity and soteriology, many ways of showing why social trinitarianism is unworkable, many ways of approaching the entire canon of Scripture as the place where we meet with God the Trinity, many ways of demonstrating the cogency of trinitarian doctrine. In all these areas, Sonderegger has provided unexpected, unconventional, and sometimes drastic new resources, and brought up astonishing modes of argument from the vasty deep. It seems to me the theological community is still in the early period of the reception of the first volume of Sonderegger’s remarkable project; how much more so this second volume! And I eagerly await further volumes—especially the Christology and the soteriology.


It was our joy to host a panel discussion on this book, featuring the contributors to this symposium. You can find the video from that event on our resource page.