is an ever more devout Catholic, and my Mom wonders if I'm not afraid of getting hit by lightening whenever I say I don't believe in God. But neither of them actually come out and tell me I'm a moron for not believing, so I give them pretty much the same courtesy.
I think it helps a lot that they are both Democrats, even, in many ways, liberals. Aside from my Dad pressuring me and sibs to come to church when we're visiting and he's lectoring, we just don't discuss religion much. I did get pretty insulted when he told me a few years ago that he was sure some day I would "come back to the church." I won't, and I never was enough of a Catholic to "go back" to it. But, I just said he was wrong without telling him how much it angered me that he said it. Then again, he also says some day I'll be mature enough to appreciate opera. That's not gonna happen, wither, but it doesn't piss me off nearly as much.
One of my four sibs is annoying in her religiosity, but I don't see her that much and so I usually let it slide. My other sibs are all atheist or may as well be. All their kids were put through the early Catholic ceremonies, more as a social/cultural thing. None are church goers.
It's my parents' siblings and their kids who I've gotten into some major disagreements with. Almost all of them are not too bright, right wing, and religious. It was them sending around right wing emails and me having the sheer audacity to respond to them that initiated most of the blow-ups.
Over time, I have found myself becoming less and less tolerant of religious people's disrespect of my right not to have their religion thrust upon me. I think it has a lot to do with the increased denials of the separation of church and state and the hateful, xenophobic, misogynist nature of religious groups.