We all have a name for our lack of belief or for just being. Everybody seems to have a reason for however they choose to refer to themselves.
When I call myself an "Atheist" I mean "with out religion." of course. That's not the only thing going on though. When I say "I am an Atheist" I mean "there is no evidence that there is a god."
When I say "I am an atheist" I mean I'll take science over religious rubbish any day.
When I say "Holy shit! I am an Atheist!" This means "You'll have to sell me on a god before you sell me on a religion." Good luck on that.
How do you refer to yourself and why?