[header] How to deal with religious people if you are an atheist [title] Don't bring up the subject unnecessarily. [step] You should never feel like you have to lie or pretend about what you believe (or don't). If you're asked about your religious beliefs, be honest. 
However, you also don't need to be a walking advertisement for atheism at all times either. [substeps] If you're in a room full of believers, think carefully before steering the conversation towards your lack of belief.