Oh, yeah. Different forms of Catholicism (esp. in the Middle Ages) really did vary a lot, generally due to the established religion. (Although sometimes even due to their founders or other influences. Ireland took a hard line against slavery long before the Catholic Church as a whole did because of the influence of St. Patrick.) So while there were commonalities, even then, it's hard to say "Christian attitudes towards women" as there wasn't a standard attitude. (It would be like saying, "Classical Greek attitudes", which is rather goofy, as the experience of an Athenian woman was radically different from that of a girl off flashing her thighs in Sparta.)

It's virtually impossible to check out of any established social system. (Note all the people, like me, who fully believe in global warming, accept that it's going to destroy the world, yet still drive. I wish I didn't have to, but there's not really a viable alternative.) The same is true in all...

I'm willing to give some leeway for historical characters. But so many writers decide that their heroine is going to be this...I'm not sure...like, feminist, anti-slavery zealot. Which I suppose she could be, but this would totally alienate her from the rest of society and probably get her locked away in some tiny room in her parents' estate rather than win her supporters.

That said, it would be kind of funny to see someone write a historical novel where their hero/heroine did behave like a modern person, with modern views and then was treated as such by the people around her. ;)