[ Aziraphale pauses, for a moment, feeling rather awkward. It's been hard enough dealing with the idea that there are different versions of himself and Crowley (and, presumably, everyone else as well) going about and crossing these different worlds, but it's a whole other thing breaking it to someone that there are worlds they may not exist in. It would also imply that he'd had to face that about himself, and he's had a bad enough time letting himself think too deeply about these things on late quiet nights. ]

Right. And, yes, I do suppose it makes it all the easier to have accurate versions for different peoples, but there's still some discussion to be had about older texts. It's an industry that's been improving over the centuries, but it's quite difficult to verify those that were made before all of it was properly available.

[ Aziraphale has never really been picky about blasphemy, not of this level, anyway. He mostly found himself concerned when he heard something that might be against Heaven's rules, when he was employed, but finding offense in interpretation or lack of somehow apparently predisposed knowledge was more of a thing humans did. ]

It's a bit more complicated than that. But the point is that his importance was immense, and therefore used as a reference by some peoples that followed His teachings.

And as far as the calendar, Julius Ceasar was mistaken about the length of the year, and the Christian churches do quite like their holidays, so they made sure to nudge the math into the right place.