Just to add a view from someone living in a progressive-ish country:

Religion and differences of religion have never played a big part in my relations with anyone, nor am I aware it has affected anyone else towards me. There are very few fundamentalists here, so nobody seems to care all that much what you believe or don’t believe.

It’s strange that someone would worry about this. I’m agnostic rather than atheist, but most of my family are very deeply into religion. And my partner is priest by profession. Never has that played a role in our relations, and we do very openly talk about all this occasionally too. They are not trying to convert me, and I’m not trying to convert them. And if nobody wants to convert anyone, there’s very little friction. All it takes is some understanding and empathy, and probably the humility to accept that any of us might be wrong, even one themselves. So nobody’s preaching to anyone, yet we can talk about these things very smoothly and openly if need be, like in regards to children and upbringing etc.

Disagreeing is healthy. Talking is healthy. Getting offended is not. Neither is trying to force anyone into anything, or even worse, unwarrantedly expecting something from someone.

So religion has played exactly zero part in this or anything else at least in my personal relations, or those who I know. I don’t think religion has anything to do with children either. Upbringing can be colorful and include everyone’s opinions and views, and the unique stuff just requires some open conversation and compromises from all parties, which is true for everything in life anyway.