I don't think you know what atheism is. One can be both an atheist and an agnostic. Atheism is nothing more than the rejection of a proposed deity. Wikipedia has a good article on the different kinds of atheism.
I'm what's known as a "soft" atheist, which is also known by the clumsier title of "atheist agnostic." I reject every claim of a god I've ever encountered, but I don't have an opinion on whether or not there is an actual "designer" or "supreme intelligence" or whatever. So I'm atheistic towards the Christian god, but I'm undecided on whether something may actually exist (though I see no evidence).
A "hard" atheist is someone who not only rejects a particular claim about a deity's existence, but also rejects the possibility of a designer or whatever.
Well, now that I think about it, I probably lean more towards hard atheism.