My immediate family is atheist. My parents and other family know. My husband's family sort of know. But my husband has not told them about himself, so I am politically quiet. Outside of family my good friends know. Others know if I really need to tell them to maintain honesty. But I don't find it necessary to say, but I'm atheist to everyone who mentions god. I do tell proselytizers at the door if I'm in the mood and have the time for the ensuing conversation. Sometimes it just scares them away.
If there is a god, I want to believe that there is a god. If there is not a god, I want to believe that there is no god.