my grip about this study is it seems to confuse the term atheist with non-religious. just because you haven't aligned yourself with one of the other relgions of the world does not make you an atheist.
an atheist believes that there is no god.
a non-religious (in the way they are using it here) means you aren't associated with any church/whatever.
as far as i'm concerned, atheisism is a religion. if you haven't given serious thought to your choice to not believe in god you are more agnostic then athiest imo.
the word belief does not equate to religious belief. i believe you are a person writing that post, not a bot. I might be wrong, but I'm pretty convinced I'm right in my belief. Is this a religious belief?
There are several god claims made by several religions and all that atheism does is say 'sorry, I don't believe your claims are fundamented'. that's it. there's no positive claim being made, it's just a response to the positive claims of religions.
Ateism doesn't exist unless religious people make claims about supernatural things. So how can you call it a religion? (atheism is as much of a religion as bald is a hair color) ;)
on a side note, agnosticism is the positive claim that 'we don't know if a god exists until it proves itself'. you can be agnostic atheist (i don't know if a god exists, but I believe it doesn't) or agnostic theist (i don't know if a god exists, but I believe it does).
so being agnostic doesn't stop you from being atheist :)