Unexplained thought of the day
Divine agency in the NT, as a christological fact (Christ is at God’s right hand, God created through Christ etc.), is useful much the same way persona / prosopon function in the early church writings: to say Christ is not God the Father. It therefore resists modalism. (It doesn’t work alone in doing this, of course, and it corresponds with the double object of early Christian faith, in God and in Jesus, as mediated and enabled by the Spirit)
On the other hand, the uniqueness of Christ as divine agent, when coupled with key explanatory conditions (the Christ-relation, “monotheistic” faith in God, epistemology etc.), corresponds to the use of ousia in the fathers. Of course, to say “Christ is an utterly unique divine agent” can be misleading. But when the import of “unique” is grasped correctly, i.e. in terms of the 1st century Jewish-Christian knowing of Christology in terms of the way 1st century Jews expressed the transcendent uniqueness of God, namely through the Christ-relation, it is simply to say that Christ is one being with Father – yet, as agent, also that he is not God the Father (modalism).
In this way, the sweep of NT theology points inexorably towards conceptual translation into orthodox Trinitarian formulations. This is one reason why tepid use of “divine agency”, as a category hermeneutically to distinguish Christ in the NT from correspondence with later orthodox divine Christology, is clumsy at best.
I realise that I should explain myself a little more fully. But see the post title.