Living in Sin was considered too sexy at the time. The mixed images of religion and sex were scandalous. Oh, and Cher, who was running around in a video with her ass hanging out of her outfit made of two leather straps somehow got blamed for it. HER videos were too provocative; she was dating Richie; therefore she had to be a bad influence.
Yeah, it was kind of strange. A couple of years later MTV was okay with airing that video for Baby Got Back which was far more sexual than Living in Sin. And it was okay for Jeremy to blow his head off in class. MTV got really lenient with their censors.