OK. I'll bite. How would you phrase the question if you were building a dating site?
Hmm. There are several options I think.
Under the heading Religion, I would want to see:
A list of religions, plus the options 'none' (for atheists and agnostics), 'no preference' (for those who don't know/care), 'none of the above' (perhaps with a 'please specifiy' text box in case it's satanism or something).
If it was to be a list of religious philosophies, or attitudes towards religion (in which atheism would properly belong), it would have to be something like:
Atheist
Agnostic
Believer in single deity
Believer in multiple deities
etc
If the question is 'Religion?' then the atheists answer is 'none'. If you ask an atheist what their religion is, they will tell you they don't have one. They won't say 'my religion is atheism'.
But, to take you literally, If
I were building a dating site, I wouldn't have a list at all, I'd have 'soft' personality questions like "is religion important to you?" and "do you believe in an afterlife?"