Someone who believes in science rather than a god or gods.
Note: This also excludes a belief in satan. Only satanists worship satan. Contrary to christian propaganda, atheists are happy, tolerant people and except in the cases of a religon being imposed upon them, they understand the diversity of beliefs, and conseal their distaste towards religon so as not to offend others.
1. Hey, you there, other atheist! Do you ever notice how we are so much happier than christians because we don't have to adhere to stupid, self contradictory rules, have Sunday morning to sleep-in, and have the knowlage that when we die, we loose all consious thought, and our bodies rot in a coffin.
2. Thankyou Mr. Atheist, without you, there'd be no TV, cars, computers, pornography or extra-warm socks because of how much christians hate science.
3. Wow, those christians sure seem angry at us atheists. Maybe its because our science has made their religon obsolete in filling the void of ignorance from thousands of years ago, and they are scared that they have based their whole lives around a fallacy, and that we are right and they are wrong.