Even if we take the premise that atheism is religion, if you're going to call atheism a cult then you must logically, implicitly admit that all religion consists of cults. But then the starting premise ultimately leads to the realm of nihilism, a self-detonating position.
Religion is about the bigoted, prejudicial thinking that dismisses the lack of evidence or evidence to the contrary in favor of a given position.
Atheism is accepting the lack of evidence and considering evidence to the contrary. You couldn't get more opposite than that.
It's in response to this video by Richard Dawkins:
Another commenter brings up Darwin's "On the Origin of Species." You can find that on line here.