You don't think atheists consider the proposition of theism directly? Or the proofs of God's existence?

We don't have direct access to reality, unless you're talking about mystical experience. Mysticism tends to leave theism behind, by depersonalizing the "Source."

Otherwise, religious beliefs, traditions, and creeds are the subject matters that are being accepted or rejected. To say that atheists reject God is to beg the question. Atheists reject theism, the proposition that a perfect person created and intervenes in the natural universe.