Rainbow Mage
Lib Democrat/Agnostic/Epicurean-ish/Buddhist-ish
Paul was mostly writing to established congregations...they didnt need to be convinced of the virgin birth because they already knew about it
why would Paul waste time and energy writing about things that were already established?
It's a stretch to assume they ascribed themselves to such a fabulous belief if Paul doesn't mention it, especially in the beginnings of a religion. Any religion I've ever studied the history of most of the fabulous, outrageous beliefs came later. I'd assume Christianity has been no different. Gnosticism is actually a part of Christianity's history, and the Gnostic texts don't outright confirm or validate the virgin birth. The Gospel of Phillip comes closest.
I will say this, whoever wrote the birth narratives didn't understand Jewish marriage custom very well.