luckily nobody in my family really believes in anything too seriously

Fair question. I honestly haven't told most of my family. I intend to use the idea of the afterlife/heaven when comforting my older family members near the end of their life.

If confronted with negativity, use their own dogma against them (Golden Rule, "turn the other cheek," etc.). Remind them that their religion dictates that everyone is equal in the eyes of the "creator," whether or not they choose to accept the mandates of their own beliefs. Most religious people tend to pick-and-choose their favorite sh**, rather than consider the teachings as a whole.
And, decide what's really worth raising a ruckus about in the first place. If I'm at a table where everyone is praying before a meal, I just lower my head and keep quiet. If someone at the table asks why I'm not participating in prayer, I just answer, "I'm sorry, but I don't discuss religion, politics, or sex at the table." That should shut them up, or announce their hypocrisy then and there.
Long story short, keep quiet, unless you're really being FORCED to do something you don't agree with. It would be fun on some level to go door-to-door and spread the word of atheism. But, we tend to be smarter and more preoccupied with better things to do. And we don't want to get shot.

Something a wise man once said fits here as good as any other thing. I Yam What I Yam & Dats What I Yam! - Popeye the sailor man. If friends can't deal with it then be sad for them, if your family can't understand, just stick with it until they do.I think that's all that needs to be said on the subject.