Atheism and Theism are equally absurd.

a·the·ist –noun
a person who denies or disbelieves the existence of a supreme being or beings.

I still say that to deny or disbelieve [verbs] implies action by an individual, which means it is not passive and thus not innate (as babies are not athiests). To deny it, the concept of God has to exist, which it wouldn't if there was no belief. Basically, 150,000 years ago there were no atheists.