Sounds like a generalization based on the fallacy of positive instances ("[tendency] to notice and remember events that confirm our expectations and ignore those that are nonconfirming.
http://jws-edcv.wiley.com/college/bc...10565_,00.html)
If you pay more attention, I'm sure you'll find just as many religious people who experience "wild sex" as those who are nonreligious. If you live in the bible belt or new orleans, I'm sure it'll be more difficult to find. However, if you broaden your perspective to the country, then it's probably even. Or, statistically speaking, there will be more religious people who have wild sex than nonreligious (since the US is predominantly religious). Those religious people who do have wild sex, I imagine, are probably less inclined to talk openly about their experiences. So the only way you'd be able to figure this out accurately is by a randomly selected representative sample of the entire US with an unbiased survey/test.