The article is basically saying that Ashely Madison users represent a fair cross section of American society when it comes to religious affiliation. Which, honestly, is not as shocking as they're trying to make it sound.
Christians are just people. It's not like our temptations are removed just because we can stand up and say that we believe Jesus is who he says he is. The only difference is that we can call on Christ to help us out in our time of weakness. It would be my opinion that Ashley Madison users claiming to be Christians aren't holding up their end of the arrangement.