I'm rewatching this years later and I'm STILL confused

[Fuzzy Necromancer]

What purpose do the monster transformations serve? Like, fart cloud satan's whole aim is getting this guy to bring out evil in the people around them, so how is that furthered by random maulings? Or is that a device to get him into trouble so he has to sin his way out, thus furthering his distillation into a Saint of Evil? Why did smokey satan think it was a good idea to have him possess this dead man's body and regain his original face?

And DAMN, how horrible was this woman's husband that she views an actual servant of the supreme evil being as a move up in the marriage department?