John Meyendorff gets the nub of Cyrillian - one is tempted to say simply orthodox - Christology in this brief statement: “God without ceasing to be God, made human nature his own to the point of mortality.”

God joins Himself to humanity, makes it His, and won’t let go. Even death cannot shake Him loose from us. When death looms, the Son doesn’t play the Nestorian and shrink back in horror. He clings to the assumed humanity even to the grave.

This is what Christology means: God literally loves us to death.

Also beyond: Because love is stronger than death. In the flesh, He passes through death and triumphs over it.

As Barth says, He wills to be God only as God-with-us, the “us” being us sinners and mortals, Dasein being toward death. Or as Jenson says, in Christ God shows Himself faithful unto death, and then yet again faithful.