For centuries, rabbis were perplexed by some Old Testament passages that seem to point to multiple persons in the Godhead. For example, what are we to make of the plural pronouns in the early chapters of Genesis? In the creation account, there is the statement, “Let us make man in our image, after our likeness” (Gen. 1:26). God says about Adam, “The man has become like one of us in knowing good and evil” (Gen. 3:22). Still later, at Babel, God says, “Let us go down and there confuse their language” (Gen. 11:7). What are we to make of the word “us” in these passages? What are we to make of the three supernatural beings who visit Abraham a little later (Gen. 18:1–21) and whom he worships (Gen. 18:2–3)? And, perhaps most importantly, what are we to make of the many appearances in the Old Testament of the angel of the Lord, who, in some passages, it is quite clear, is divine and yet also distinct from Yahweh (e.g., Ex. 14:19–22; Judg. 6:11–24)?
In the exegesis of the early centuries and later, in the Reformation period, it was typical to see in these passages preincarnate appearances of Christ. There is something to be said for this view. Christ himself declared that one of the most stringent assertions of Isaiah was made because the prophet saw Christ’s “glory and spoke of him” (John 12:41). If Isaiah saw Christ’s glory long before the time of the incarnation, Christ might well have manifested himself in a nonincarnate way in the person of the angel of the Lord. And yet, without the full light of the incarnation shining back onto the Old Testament revelation, it is difficult to see in it a full doctrine of the Trinity. It was the incarnation that made inescapable what had, of course, been there from all eternity but was only hinted at in the earlier biblical record: God is one in being but also tripersonal.