Assume that the Son’s personal
existence is equally constituted by the unity of the divine and human natures
in a single person, i.e., that both natures are equally essential to the person
of the Son. Then either there was no Son until his human nature came into
existence or else he is “always ready” or timelessly incarnate. The former
possibility is incompatible with the idea that the Son is eternally begotten by
the Father insofar as it would imply that the Son did not always exist. This
“Arian” option was condemned at the first Council of Nicaea. The latter
possibility would mean that there is no λογος
ασαρκος, i.e., no unincarnate Word. The Son or Word
is rather essentially and necessarily incarnate. It also implies an
“eternalist” conception of things according to which reality is a single
“block” extended along four dimensions. Time does not truly pass and becoming
is not a genuine dimension of reality. Things rather always, simply, and
timelessly are. Only thus could not say that the human nature of the Son and
thus the Son himself does not really come into being but simply always and
timelessly belongs to him. This further means that the Son never becomes
incarnate. It would not be true that the Word “became” flesh (John 1:13). He is
rather timelessly incarnate.
Grant that the human nature of Christ
is just as constitutive of his personal existence as his divine nature. One may
also ask the question of whether the human nature of Christ exists necessarily
or contingently. If it exists contingently, which is to say that it does not
have to exist, then it follows that the Son also does not have to exist, since
his personal existence ex hypothesi is constituted by and thus requires
the reality of the human nature. This is incompatible with the Nicene idea that
the Son is necessarily and eternally begotten from the ουσια of the Father. On the other hand, if the Son
exists necessarily and thus also his human nature, then it follows that the
created order with which the human nature is inextricably connected also exists
necessarily as constitutive of God’s own existence in the person of the Son.
There can be no human nature without a world in which it can exist. There is no
human life, without a certain moment and place of birth, and so on. This is
inconsistent with the catholic idea of creatio ex nihilo. God is
supposed to have created the world ex nihilo. But if the Son is
necessarily human, then the world would by extension be constitutive of God’s
existence in the person of the Son, and God could hardly have created himself ex
nihilo. (Steven Nemes, Trinity and Incarnation: A Post-Catholic Theology
[Eugene, Oreg.: Cascade Books, 2023], 71-72)