Virgin Mary and Original Sin
Menstruation is a result of original sin, right? But, according to the concept of immaculate conception, Mary was born without sin. Therefore, she would not have menstruated. So, how could she have conceived Jesus without a menstrual cycle? A miracle, I suppose.
The worst problem with original sin though is the stupid “your baby will be stuck in limbo” concept. But, thanks to some theological backtracking, in 2007 the infallible Pope has declared limbo a thing of the past. Which begs the question, is that retroactive? Do the babies that had already been sent to limbo stay there? Or do they get released?