What do I do when religious people solicit me at work?

Try to be polite and tell them that you are not allowed to have personal conversations at work, but will be more then happy to assist them in what ever they need in the store. Also, I live in the Bible Belt as well, and if you get fired for being an Atheist, it is still classified as discrimination, you can get a lawyer, take it to Wage and Hour, sue and win. They are prohibited from termination based off of religious beliefs, or atheism. No matter how bad they want to, that's Federal Law, which Wage and Hour has to go by when hearing a case. Plus, it is not your fault the customer brought it up.