Finally we have the formula for the Trinity identity.
Trinity and Identity
Can one consistently believe (1) – (7)? It depends on how we read the “is” in (1) – (6). If we read it throughout as the “is” of strict identity, as “=” the answer is no. Identity is an equivalence relation: it is reflexive, symmetric and transitive, which is to say, for all x, y and z the following hold:
Reflexivity: x = x
Symmetry: If x = y then y = x
Transitivity: If x = y and y = z then x = y
In addition, identity is an unrestricted indiscernibilty relation for all properties, which is to say it obeys Leibniz’ Law, understood as the Indiscernibility of Identicals:
LL: If x = y then for all properties, P, x has P if and only if y has P
This is bad news. Suppose we read the “is” as “=” in (1) – (6). Then it follows from (1) and (2), by symmetry and transitivity, that the Father is the Son, which contradicts (4). Put another way, given LL, (1) entails that God has all the same properties as the Father, including the property of being identical with the Father insofar as everything has the property of self-identity. (2) says that the Son likewise has all the same properties as God. It follows that, since God has the property of being identical with the Son, the Son also has the property of being identical with the Father, which contradicts (4).
These formal features of identity are non-negotiable in the way that the four-sidedness of squares is: God cannot evade them any more than he can make a square with only three sides. God can make triangles—and pentagons, chiliagons or figures with any number of sides he pleases—but he cannot make such things squares. So, assuming that “God,” “Father,” “Son” and “Holy Spirit” don’t change their reference, the “is” that figures in (1) – (6) cannot be the “is” of strict identity.