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).
Geerhardus Vos (1862–1949)
God’s being may not be called personal in the abstract but only in His threefold existence as Father, Son, and Holy Spirit. In God personality is not one but three. There are not four but only three persons in the Godhead. (17)
17. Must we ascribe personality to God’s being in itself?
No, for then we obtain four persons. The essence, however, is not impersonal for it exists in three persons. Only if one abstracts the essence from the latter can one say that it is not personal. (43)
Cornelius Van Til (1895–1987)
We speak of the essence of God in contrast to the three persons of the Godhead. We speak of God as a person; yet we speak also of three persons in the Godhead. As we say that each of the attributes of God is to be identified with the being of God, while yet we are justified in making a distinction between them, so we say that each of the persons of the Trinity is exhaustive of divinity itself, while yet there is a genuine distinction between the persons. Unity and plurality are equally ultimate in the Godhead. The persons of the Godhead are mutually exhaustive of one another, and therefore of the essence of the Godhead. God is a one-conscious being, and yet he is also a tri-conscious being.
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. . . the work ascribed to any of the persons is the work of one absolute person. . . .
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It is sometimes asserted that we can prove to men that we are not asserting anything that they ought to consider irrational, inasmuch as we say that God is one in essence and three in person. We therefore claim that we have not asserted unity and trinity of exactly the same thing.
Yet this is not the whole truth of the matter. We do assert that God, that is, the whole Godhead, is one person. We have noted how each attribute is coextensive with the being of God. We are compelled to maintain this in order to avoid the notion of an uninterpreted being of some sort. In other words, we are bound to maintain the identity of the attributes of God with the being of God in order to avoid the specter of brute fact. In a similar manner we have noted how theologians insist that each of the persons of the Godhead is co-terminous with the being of the Godhead. But all this is not to say that the distinctions of the attributes are merely nominal. Nor is it to say that the distinctions of the persons are merely nominal. We need both the absolute cotermineity of each attribute and each person with the whole being of God, and the genuine significance of the distinctions of the attributes and the persons. “Each person,” says Bavinck, “is equal to the whole essence of God and coterminous with both other persons and with all three,” (“Elk persoon is daarom gelyk aan het gansche wezen en evenveel als de beide andere of als alle drie saam”). Over against all other beings, that is, over against created beings, we must therefore hold that God’s being presents an absolute numerical identity. And even within the ontological Trinity we must maintain that God is numerically one. He is one person. When we say that we believe in a personal God, we do not merely mean that we believe in a God to whom the adjective “personality” may be attached. God is not an essence that has personality; He is absolute personality. Yet, within the being of the one person we are permitted and compelled by Scripture to make the distinction between a specific or generic type of being, and three personal subsistences.
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. . . To say that God is one person and at the same time to say that he exists as three persons, he will say, is not merely to contradict yourself verbally, but is to say that all predication is analytic. It is to assert that being is already fully complete; that it cannot be added to. All the difficulties that Parmenides faced are thus said to face the Christian believer.
Cornelius Van Til, “The Trinity of God,” chapter 17 of An Introduction to Systematic Theology (Phillipsburg, NJ: Presbyterian and Reformed, 1979), 229ff. Cf. John Frame, “Father, Son, and Spirit,” chapter 27 of The Doctrine of God, vol. 2 of A Theology of Lordship (Phillipsburg, NJ: P&R), 703ff.
Gordon Clark, a contemporary of Van Til’s, considered the key issue avoiding contradiction:
[T]he Godhead [is] one in one sense and three in a different sense. Whether this difference be called person or substance is inconsequential. . . . Although it is not familiar to our ears, one could say that God is one person and three substances. In fact, translate substance back into Greek and it is most orthodox to say that the Godhead is three substances. It makes no difference what term one uses, provided that he clearly states that they are not synonymous. God is one and three in different senses. (The Trinity [Jefferson, MD: Trinity Foundation, 1985], 52–53)
See also “Is the Trinity One ‘What’ and Three ‘Who’s’?”