Why do religious people desperately want to class Atheism as a religion?

[robvalue]

Default atheism is not a belief, it's a lack of a belief. So it can't possibly be a worldview, or anything else. It is what it is, and nothing more.

The fact that default atheism makes no claims frustrates some people I think, so they have to build up pretend worldviews to attach to it in order to have something to attack.

Also, I think some people are so heavily invested in a religious worldview that they can't imagine any "replacement" being anything else.