Orthodox Apologetics

""As is known, the final formulation of the doctrine of the Holy Trinity speaks of  "one substance, three persons" (μία ουσία τρία άτομα). One would therefore have said that the unity of God, the "ontology" of God, consists in the substance of God. This would bring us back to the ancient Greek ontology: God first is God (His substance or nature, His being), and then exists as Trinity, that is, as persons. This interpretation in fact prevailed in Western theology and unfortunately entered into modern Orthodox dogmatics with the arrangement in the dogmatic handbooks of the headings "On the One God" followed by "On the Trinity." The significance of this interpretation lies in the assumption that the ontological "principle" of God is not found in the person but in the substance, that is, in the "being" itself of God. Indeed the idea took shape in Western theology that that which constitutes the unity of God is the one divine substance, the one divinity; this is, as it were, the ontological "principle" of God.

But this interpretation represents a misinterpretation of the Patristic theology of the Trinity. Among the Greek Fathers the unity of God, the one God, and the ontological "principle" or "cause" of the being and life of God does not consist in the one substance of God but in the hypostasis, that is, the person of the Father. The one God is not the one substance but the Father, who is the "cause" both of the generation of the Son and of the procession of the Spirit. Consequently, the ontological "principle" of God is traced back, once again, to the person. Thus when we say that God "is," we do not bind the personal freedom of God - the being of God is not an ontological "necessity" or a simple "reality" for God - but we ascribe the being of God to His personal freedom.

In a more analytical way this means that God, as Father and not as substance, perpetually confirms through "being" His free will to exist. And it is precisely His Trinitarian existence that constitutes this confirmation: the Father out of love - that is, freely - begets the Son and brings forth the Spirit. If God exists, He exists because the Father exists, that is, He who out of love freely begets the Son and brings forth the Spirit. Thus God as person - as the hypostasis of the Father - makes the one divine substance to be that which it is: the one God. This point is absolutely crucial. For it is precisely with this point that the new philosophical position of the Cappadocian Fathers, and of St. Basil in particular, is directly connected. That is to say, the substance never exists in a "naked" state, that is, without hypostasis, without "a mode of existence." And the one divine substance is consequently the being of God only because it has these three modes of existence, which it owes not to the substance but to one person, the Father. Outside the Trinity there is no God, that is, no divine substance, because the ontological "principle" of God is the Father. The personal existence of God (the Father) constitutes His substance, makes it hypostases. The being of God is identified with the person.

3. What therefore is important in Trinitarian theology is that God "exists" on account of a person, the Father, and not on account of a substance. Because it's significance is not simply theoretical or academic but profoundly existential, ..........................."" [1]

"The manner in which God exercises His ontological freedom, that precisely which makes Him ontologically free, is the way in which He transcends and abolishes the ontological necessity of the substance by being God as Father, that is, as He who "begets" the Son and "brings forth" the Spirit. This ecstatic character of God, the fact that His being is identical with an act of communion, ensures the transcendence of the ontological necessity which His substance would have demanded - if the substance were the primary ontological predicate of God - and replaces this necessity with the free self-affirmation of divine existence. For this communion is a product of freedom as a result not of the substance of God but of a person, the Father - observe why this doctrinal detail is so important - who is Trinity not because the divine nature is ecstatic but because the Father as a person freely wills this communion." [2]<>