Pro Choice or Pro Life?

I know personally many people who are on both sides and it seems like pro-life is a heavily religious view...my question is why are you pro-life? And why do some treat pro-choice people like their side is outright wrong?
I'm not judging anyone for being one way or the other, I'm just curious as to why? It seems to me like the super religious pro-life people aren't nice enough to respect others choices. Again, not judging just discussing & speculating.