Orthodox trinitarianism typically refers to God in terms of three persons or subsistences (personas, subsistentia, or ὑποστάσιες) and one essence or substance (essentia, substantia, or οὐσία). But is there a sense in which God is one person? To put it another way, is God’s oneness personal?
Here’s how three Princeton theologians addressed this topic.
B. B. Warfield (1851–1921)
The elements in the doctrine of God which above all others needed emphasis in Old Testament times were naturally His unity and His personality. The great thing to be taught the ancient people of God was that the God of all the earth is one person. Over against the varying idolatries about them, this was the truth of truths for which Israel was primarily to stand; and not until this great truth was ineffaceably stamped upon their souls could the personal distinctions in the Triune-God be safely made known to them.
Benjamin Breckinridge Warfield, “The Spirit of God in the Old Testament,” chapter 3 of Biblical Doctrines, vol. 2 of The Works of Benjamin B. Warfield (New York: Oxford University Press, 1932), 127 (emphasis added).