So what the hell is an atheist, really?
This question has been done to death, (just see my blogroll or a google search for some in-depth discussions of the subject), but I thought I'd take a stab at it anyway.
An atheist lacks belief in god(s), by the majority of definitions of the word "god."
I don't believe in a white-bearded man in the sky throwing down lightning bolts. I don't believe in a being that created the world 6000 years ago in the Garden of Eden. I don't believe in a force that consciously and knowingly set off the Big Bang billions of years ago. I don't believe that Jesus, if he existed, was a special, divine person. I don't believe in an impersonal presence or "essence" in nature that is divine. I don't believe in Jehovah, Shiva, Allah, Krishna, Zeus, Athena, Isis, Ishtar, Yahweh, etc...
I do not claim that these gods or any others do not exist, just that I have no evidence or belief in them. Some atheists would claim that gods do not exist, and that position can be called "strong" atheism. 'Weak" atheism is much more common. If you do not have a clear, definitive belief in a god or godlike higher power, then YOU ARE AN ATHEIST, no matter what you want to call yourself.