I didn't know this until reading Hitchens' book: some Xians believe that the virgin Mary would not have been pure enough to carry god's seed unless she herself was conceived immaculately. Are you kidding me? Doesn't this set up an infinite regress? If Jesus could not have left Mary untainted by original sin, then she too would still be tainted by original sin unless her mother was an immaculate conception and so on. So, not only do some Xians posit that a woman got preggers without having sex, but so did her mom. Something that we know is biologically impossible happened not just once, but twice.
What is it about being virginal or not having sex that makes one pure? Why is sex considered dirty and why do Xians have such a pre-occupation with the sex of others? This compulsion to label anything sexual as shameful is one of the more perverse parts of Xianity. Apparently god gave us something enjoyable and necessary, then decided that it was a bad thing we should avoid. But he gave us free will as well; which is a bad thing in his eyes, since he made us vulnerable to temptation. Is there anything about Xianity that makes sense?