God did not reveal himself in clearly defined Trinitarian terms in the OT. To do so would have provided needless temptations to polytheism in the light of ancient culture. But the OT prepares for the doctrine of the Trinity in several ways: (1) It uses a plural word for God (elohim) with singular verbs (Gen. 1:1 and often). (2) It employs various triadic formulas in reference to God (e.g., the three - man visitation of Gen. 18:2, the triple name of the God of the patriarchs in Exod. 3:15 and often, and the thrice - spoken "Holy" of Isa. 6:3). (3) The "angel of God / the Lord" sometimes refers to God as his sender, sometimes speaks as though he himself were God. (4) Father, Spirit, and Word are all active in creation (Gen. 1:1 - 3; see also John 1:1 - 3).