My wife is a Lutheran (I call her a lapsed Lutheran cuz she is Lutheran in name only lol), I am an atheist.
It causes us zero problems. I like certain "religious"-type ornaments in my house for their ascetic value, we celebrate secularized Christmas and Easter, and we don't go to church. My wife did get pretty butt-hurt when I objected to my son getting baptized because "he doesn't have a soul." She didn't take that one too well LOL.
I later recanted and said he can get baptized if it will make her feel better but I don't want him indoctrinated into anything until he is old enough to look for answers himself.