Not sure if I follow you or get your point.
I'm a conservative Christian (not practicing any particular brand, I have a healthy mistrust of all organized religions). My point being, I've never "unfriended" someone, either on line or IRL just because they were an atheist.
That being said, perhaps it depends on what kind of atheist you are? Are you the kind that has to mention it all of the f**king time? (Kind of like that one "friend" that always mentions that they're vegan, or gluten free, or that they quit smoking or drinking, or that they're Christian. People like that will annoy me to the point of defriending or avoiding them.)