It's a clever line. When Christopher Hitchens slams Christianity he does it with style. "If we lost all our hard-won knowledge and all our archives, and all our ethics and all our morals...and had to reconstruct everything essential from scratch, it is difficult to imagine at what point we would need to remind or reassure ourselves that Jesus was born of a virgin."
The line employs a sharp edged bathos: End of civilization drama counterpoised with a sneer at that most-despised of pre-modern Christian dogma - the virgin birth. Religious people gasped, and aggressive atheists snickered, but I sat there wishing that Christopher Hitchens knew more history.
When our civilization did indeed collapse - when the Goths tore the gates of Rome from its hinges and mobs of tattooed warriors raped and pillaged their way across what had formerly been the civilized world; when most of "our hard-won knowledge and ... our archives" were burned in Alexandria -- we felt compelled over and over again to remind ourselves of exactly that: Jesus Christ was born of a virgin. I guess I can't expect Chris Hitchens to acquire CS Lewis' knowledge of medieval history, but at least he could have read Cahill's How the Irish Saved Western Civilization.
It's there so often in medieval literature that even a very poor Protestant Latin student like me can read it without stopping to translate. "Christus natus est, ex Maria virgine." Christ is born from Mary, the virgin. They wrote it, they read it, they memorized it, and they taught it. At night they sung it in their monasteries while they copied and preserved the ancient texts of classical learning. They prayed it in the morning and then went out and turned swamps into farmland. They invented agriculture, books (as opposed to scrolls), the standard alphabet, the hospital, and the university.
Despite what Lewis calls the 'historical snobbery' of modern Western secular elites towards the middle ages, the doctrine of the virgin birth is not based an ancient anti-sexual 'hang-up'. It would be crazy for Gospel writers like Matthew and Luke to write anti-sex books that begin with the genealogy of the Savior. In the biblical world picture, children are a good gift from God. Barrenness is a source of sorrow. Isaac's mother, Sarah, was barren. So were Samuel and Samson's mothers. The world of Mary and Joseph was filled with the stories of barren women, some so old that they were considered to be a lost cause. But in these stories, something happens. Angels come and announce a coming child, a child of promise. Isaac would become the father of Israel. Samson would deliver the Jews from the tyranny of foreign oppression. Samuel would break the bonds of home-grown corruption.