I'm totally with you being an Atheist with a big A myself. I was lucky enough to grow up in Norway though where the large majority are Atheists (or express no religious affiliation).

Anyways, to me the best behavior is to just be a realist and an objectivist. Be the person who asks skeptical questions and demands evidence and reason, and then be consistent with that both with regards to religon and other topics. As Sam Harris put it in a speech I really enjoyed: We don't have a word for non-astrologers, and we shouldn't need a word for non-believers, we should just celebrate reason.