If you go to: http://blog.okcupid.com/index.php/the-real-stuff-white-people-like/ you can find an interesting analysis of the user base of the dating-site “OkCupid”.
The point I personally found most interesting is the literacy level of the profile-description over religious-belief.
And further more, if you divide the groups in subgroups of how serious they are with their belief:
“Note that for each of the faith-based belief systems I’ve listed, the people who are the least serious about them write at the highest level. On the other hand, the people who are most serious about not having faith i.e. the “very serious” agnostics and atheists score higher than any religious groups.”