it occurs to me that some of us need a refresher on the terms agnostic and atheist. i can understand the confusion because i muddy the waters myself. but here is the explanation for why i (and any other atheist) is or should be an agnostic.
agnosticism (greek - "without knowledge") refers only to what is known or knowable. You can use the word in reference to gods or any other body of knowledge. i am "agnostic" on the topic of fairies and global warming. i cannot claim absolute knowledge where none exists.
atheism (greek "without god") refers only to our opinion (not "knowledge") of the existence of gods. it says nothing about what we
i used to be a defacto agnostic. i claimed that i did not know whether or not gods existed but REALLY hoped there were. after careful reflection, i came to the conclusion that it is overwhelmingly obvious that no gods likely exist. that positive assertion makes me an atheist.
but i cannot "know" with absolute certainty that there are no gods. so i am an agnostic with respect to that "knowledge."