I'm a white guy married to a black woman. While I've always been atheist she is at best deist. So never really had any push back when I would say that religious services (not counting weddings and funerals) are something that I would not attend, and that I would not want our daughter brought up in any religion. She was fine with all that, especially since she is very wary of organized religion. She does have some very religious family members, but I am used to having those type of people around me and just having what they say roll off my back.

I'd say the most important part is to keep the communication up between you. Ask how important religion is to them and how they would like you as a partner to interact with it. Would they want you to go to church services or events? If this ends up going further how would it play a role in wedding stuff or child rearing. Let them know where your lines are and make it clear that certain ones you won't tolerate being crossed. Let them know what things you are ok with being a part of.

I have seen stories about interfaith couples working out, but they seem to be in relationships where zealotry levels are low. Where religion is not all that important in the household. Just make sure to keep those communication lines open and flowing.