I try not to -- and I don't unless someone attacks my lack of belief, but I believe most of the attacking is done by new atheists. When someone finally figures out religion is a myth, it can make them angry -- they've been deceived -- and they lash out at those who still believe.
Years ago, I used to feel like that, but as time passes, atheists mellow and begin to appreciate people who take the best from their faith -- things like being charitable, kind, forgiving, and gracious to others -- and serving one's country -- and we then can see that religion has its place. Even if we have moved on -- we can appreciate the faithful.
The only time I'll say anything negative about religion is when it's used as an excuse to try and force behavior (stop same-sex marriage or abortions) or insist that non-religious people abide by religious principles. I will sometimes correct a religious person when they make blanket statements about their religion being better -- for example -- I recently asked Elvira (who thinks the JWs are the only true Christians) why they had removed some of the scripture in the King James Bible from their translation. She didn't answer me, of course, but I felt it was suitable given her aggressiveness.
But, as long as someone is nice to me -- I'm nice to them. And, if you enjoy your religion, more power to you!
