[Esaias]

It's not binitarian. Binitarianism is the belief in two divine persons in the godhead (binitarianism was a brief stop on the way to trinitarianism in the antenicene world).

Bernard's explanation of Christology is weak, in my opinion. Drysdale's is quite Nestorian, others have offered explanations that range the gamut of all known Christologies familiar to trinitarians.

I believe it is a mystery, as Paul referred to it as a mystery. Indeed, a "great" mystery without any controversy. That is, there is no controversy about the fact that the Incarnation is indeed a great mystery.

There are some things we can be certain of:

God was manifest in flesh.
Christ is the son of God.
Christ is a genuine human being.
Christ is Jehovah Who created everything.
God is ONE, not two or three.

Getting into the mechanics of the incarnation is fraught with difficulty, because the explanations we seek to provide are often simply not given in Scripture. So we are prone to errors in our choices of terms and in our presentations and explanations.

Honestly, the BEST explanation I have read is by Servetus in his On The Errors Of The Trinity. It is not perfect, but it is the best I have read so far.