If religion is mentioned, I say I am an Atheist but I don't advertise it. Sometimes I ask sneaky questions to create a little doubt but I try not to start an argument.

I don't go around announcing that I'm an athiest but if the subject ever comes up I will let it be known what my beliefs are. Presently I live in a senior apartment complex administered by the CATHOLIC CHURCH Everyone knows I am an athiest but for the most part they have accepted my beliefs.

In real life I don't bring it up if it doesn't come up. If it comes up I talk matter of factly about it. In practice it's not an issue (of course I don't live in the Bible Belt either, I live in a sane part of the country where religion and politics aren't discussed except by invitation).