That Christ was born of a virgin means the complete contradiction of all human possibility.
It is not as if God could not have brought his Son into the world in another way. We need to remember that Jesus was truly and fully human, and there is no obvious reason why he could not have been born in the usual manner, with a human biological father. But the exclusion of human initiative and activity at precisely this point underlines what is happening here: God himself is taking the initiative, God himself is coming to save.
We need to see clearly that the role of the virgin Mary is not to be the height of humanity, the chosen product of human history, prepared by grace and made ready (or perhaps even worthy!) to be the Mother of God. Far from it. That she is the Mother of God is the accomplishment of divine fiat. Not even her faith and acquiescence represents a cooperation with God. The angel, after all, doesn't come with an offer which she can accept or refuse, but with an announcement: this is happening! Mary's own 'fiat' is to her credit, but it is only an echo of the divine. All is grace.
When Christ returns, and rights all wrongs, and ushers in eternal life - well, that too will be a one-sidedly divine accomplishment. All our working and watching and praying will not bring in the new age. At best, all of those things are just our own echo of the divine 'fiat', our acknowledgement that in the life, death, and resurrection of Jesus, all is done. Like the blessed virgin after the annunciation but before the birth in Bethlehem, we have heard God say that it will be, and we have said in response: so be it.
And after that, the wait.