Is atheism a belief?

[Belacqua]

You don't know if there are specific criteria. It could be all kinds of other things, like having experienced the hypocrisy of religionists, abuse from religionists, and all sorts of other unconscious or sub-conscious aversions.

That's true.

There are all kinds of reasons why people can reject claims. There are good reasons and less good reasons. That's why it's good for us to be aware of our reasons and not claim that we don't have them.