Atheism is just rejecting the claim that Hod or a specific God claim exists, it isn’t claiming that you believe with certainty he does not. I am an agnostic atheist, I reject the claim that the Jewish, Christian, whatever God exists and in fact positively believe they do not exist because of its self-contradictory nature. I admit that there might be a higher power that created our universe and is outside of time, etc, but it’s unknown/unknowable.