(3) Whether an exclusive term, which seems to exclude otherness, can be joined to an essential name in God?
(4) Whether it can be joined to a personal term? _______________________
FIRST ARTICLE [I, Q. 31, Art. 1]
Whether There Is Trinity in God?
Objection 1: It would seem there is not trinity in God. For every name in God signifies substance or relation. But this name "Trinity" does not signify the substance; otherwise it would be predicated of each one of the persons: nor does it signify relation; for it does not express a name that refers to another. Therefore the word "Trinity" is not to be applied to God.
Obj. 2: Further, this word "trinity" is a collective term, since it signifies multitude. But such a word does not apply to God; as the unity of a collective name is the least of unities, whereas in God there exists the greatest possible unity. Therefore this word "trinity" does not apply to God.
Obj. 3: Further, every trine is threefold. But in God there is not triplicity; since triplicity is a kind of inequality. Therefore neither is there trinity in God.
Obj. 4: Further, all that exists in God exists in the unity of the divine essence; because God is His own essence. Therefore, if Trinity exists in God, it exists in the unity of the divine essence; and thus in God there would be three essential unities; which is heresy.
Obj. 5: Further, in all that is said of God, the concrete is predicated of the abstract; for Deity is God and paternity is the Father. But the Trinity cannot be called trine; otherwise there would be nine realities in God; which, of course, is erroneous. Therefore the word trinity is not to be applied to God.
On the contrary, Athanasius says: "Unity in Trinity; and Trinity in Unity is to be revered."