Atheism as opposed to agnosticism is a statement of certainty. True belief in an unproven assertion is an act of faith. I will leave it to the reader to decide if this specific act of faith constitutes a religion.
I'm not sure about that. The only time I care about religion is when I see BADecker post nonsense. Otherwise I spend no time thinking or caring about religion at all. Is rejecting even caring about the existence of god atheist or agnostic?