No, atheism is the outright rejection of the idea of God. It is a religious belief in itself that requires a faith in the non-existence of any sort of God.
And you also forgot one definition. Namely that of religion:
Religion is the belief in and worship of a god or gods, or a set of beliefs concerning the origin and purpose of the universe.
Please explain what god or gods i believe by not believing in god?
Please explain what atheists believe in?
I am an atheist by definition. Not by belief.