Question about atheism?

I've never been a very strong Christian, and I've never really cared much about what people do or do not believe (although I do find other religions/beliefs interesting). I've given it a lot of thought, and I think I'm going to turn to atheism. I don't know how to tell my friends and family though. I'm sure my parents won't care and some of my friends, but there are other people I really care about who are very devout Christians and I don't want to lose them as friends. Any advice on what to do? Thanks =)