If it is of population (which it really looks like), then at least in the US Catholics comprise 24% of the population, yet only 22.75% of the cheaters, thus making them less likely to cheat on average. But I don't know what the percentage was in their sample.
Well, I'm still looking when I have the spare time to read through what I am able to find. Valid data regarding "whose cheating who, whose being true, who don't even care anymore, whose not doing right to someone tonight and whose car is parked next-door" is scarce as we might imagine.
You and I might set up a booth on Sundays outside different churches, denominations and faiths to survey men and women coming out of church service but how valid would the data be? Try worthless.
We could survey damn near anywhere in public and be all but guaranteed that the results will be skewed depending on the location.
From what I have read evangelicals are a fairly lusty group as far as sexual infidelity is concerned and I believe that includes Catholics. People who attend church regularly reportedly are less inclined to be out slipping in the darkness. Jews, not so much.
"Jew want to fool around?" Apparently Jews are less inclined toward sexual infidelity. I'm not sure why that would be. From personal experience, pre-maritally and after divorce, Jewish girls rock in rack as a general rule.
I've mentioned this before but I first became interested in the topic of religious orientation and sex when I lived with a clinical social worker who specialized in sexual counseling. She'd come home and talk about her day, as we all do. Of course she'd never divulge any information that would identify a client. She was very careful about that. I didn't care and didn't want to know anyway.
She was supervised by a psychiatrist. They'd talk. He would give her things to read. As I became interested, she'd share many of the articles and the research with me. I found it very interesting.
Sociology fascinates me. Psychology? Meh. If one guy is into masturbation on a unicycle in rush hour traffic I find it mildly amusing and I would be only slightly curious. If scores of people were doing it in different locations across the country I would be extremely interested in knowing why.
Early in our evening discussions I was fairly judgmental of the people she might mention. Over time and after reading and later over drinks with a very close friend who was a Ph.D type clinical psychologist and the regional director for a mental health program (we'd never discussed it before as I wasn't at all curious about it up to that point) I became much less judgmental and more interested.
Bottom line:
People do cheat. We all know people who have or who do. They represent almost every faith and no faith. We do not know most people who cheat, but there are many who do, and for different reasons.
People are promiscuous: To paraphrase Oscar Wilde, "A promiscuous person is someone who is getting more sex than you."
People are kinky: No one is going to talk a lot about it, but Kinsey proved the world is kinky and studies have been proving it every since. There really is no "normal" sex.
Sexual infidelity, promiscuity and kinky happen frequently across all social and religious strata. What may vary is the social or religious
interpretation of the behavior but the interpretation doesn't much alter the behavior. That then seems to make it most difficult to conduct valid research regarding sex and religion; not impossible but difficult.