Augustine on the Trinity

In summarizing the argument of the first seven books of de Trinitate , Luigi Gioia ( The Theological Epistemology of Augustine’s De Trinitate ) distinguishes between the “outer layer” of the opening books of de Trinitate, which concerns the mystery of the Trinity especially as revealed in Scripture, and the “inner layer,” which has to do with the knowledge of God.

Regarding the outer later, the key issue has to do with the apparent separation of activity among the Persons as reflected in the New Testament. According to Augustine’s inherited Nicene orthodoxy, the three Persons act inseparably, yet the New Testament attributes some actions to the Father, some to the Son, some to the Spirit. Does the biblical portrait of the persons then violate Nicea?

Before he reaches that question, Augustine offers a biblical defense of the deity of the Son and Spirit.

His (very Athanasian) assumption throughout is that “there cannot be any intermediate being between God and his creatures.” Beings are either divine or created. To make his case, Augustine pays particular attention to the problem passages that appear to teach the subordination of the Son. In dealing with these passages, he proposes two rules. The first, drawn from Philippians 2, distinguishes between statements concerning Christ according to the “form of God” rule and statements that assume the “form of man.” At this point of the treatise, the distinction is rather clumsy, and Gioia says that “Augustine becomes increasingly aware that the relation between the humanity and the divinity of Christ is more than a simple question of the attribution of his actions to each of the two natures.” Eventually, he develops a more sophisticated framework that allows him to speak of a deus cruxifixus .

The second rule Gioia describes as the “God from God” rule. This rule provides a way of dealing with the apparently subordinationist passages in the Bible. Assuming that the Son is equal to the Father, we still have to deal with Scripture passages that speak of the Son’s derivation from the Father. By this rule, Augustine takes these passages as implying not ontological subordination but “direction.” The Father alone is deus without qualification. The Son and Spirit are deus a deo or deus ex deo . Gioia says that this rule is derived from Augustine’s meditation on the economy, on the missions of the Son and Spirit. The missions reveal the processions, and the fact that the Father never undergoes missio points to the ontological distinction between “God” and “God from God.”

Raising the question of mission raises the question of the uniqueness of the incarnation and Pentecost, and that pushes Augustine to a consideration of the Old Testament theophanies. Augustine has been regularly criticized for saying that the Person involved in the theophanies is sometimes indeterminate, but Gioia says that “Augustine is simply saying that revelation of the Trinity only occurred with the Incarnation and Pentecost.” The Old Testament gives us only hints, and even these hints must be examined in the light of the full revelation of the New Testament. Given the comparative obscurity of God’s Triune character in the Old Testament, the theophanies are indeterminate.

The inner layer of the argument is about how we know God. For Augustine, the answer to the question of knowing God is necessarily a Trinitarian and Christological answer: We know God in Christ. The invisible God makes Himself known when He comes into our ken in the incarnation. Even when he discusses the theophanies, his real concern is to understand how God makes Himself known in the Old Testament.

Beginning in Book 4, Augustine turns to the question of why God would make Himself known in the first place. The outer layer seems a bit of detached Trinitarian speculation; the inner layer of the argument is about God’s interest in man and man’s interest in God, and about how God makes Himself known. Augustine’s answer to that is in terms of “the identity between God’s self-revelation and the reconciliation accomplished through Christ in the Holy Spirit.” Trinitarian theology cannot be detached from soteriology, nor vice versa. To make Himself known, God has to do it in a way that heals both our pride and our despair. Sin thus is the central question in considering the knowledge of God. And the soteriological movement of Son and Spirit, of God from God, expresses the inner reality of God Himself.

Unlike other readings of Augustine, Gioia does not believe that there is a breach in the argument between Books 4 and 5, between the review of the economy of salvation in Books 1-4 and the anti-Arian polemics of Books 5-7. Both sections are concerned with anti-Arian polemics, the first with the Arian use of Scripture and the second with more technical Arian concerns. The inseparability of the Persons expounded from Scripture in the opening books becomes the central topic in Books 5-7. The whole first half of the treatise is also tied together by an emphasis on the missions of the Son and Spirit. In short, book 5 does not mark a new departure.

Gioia does see Book 4 as crucial to the opening arguments. There Augustine first brings the inner layer of his argument into the open, but that inner layer is there from the beginning and throughout. Throughout the opening books of de Trinitate , Augustine ultimately pursues the basis for enjoying God: “The fullness of our happiness, beyond which there is none else, is this: to enjoy God the Trinity in whose image we were made.”