I have this feeling, and I'll try to express this correctly...that Jodi discovered a Religion (Mormon) that she felt would assist her in controlling her "man" given their traditions (I apologize if that is not the correct word) regarding dating, wards, marriage, sins and confessing to Bishops or Elders etc.
They are a close knit group, the youth especially, kind of police each other, they pair off by certain ages with marriage in mind (it is encouraged, pair off meaning they are dating with marriage in mind) and this was all very comforting to her. NOT only did she meet a man she instantly became obsessed with, he is in a Religion that promotes marriage and fidelity and spirituality. This would keep him rather safe and he will HAVE to marry her.
She forgot the free will part and that he started having doubts about her. She thought she had this in the bag and it went poof. She really used this religion against him. I believe she did read most of the book of Mormon but not for honorable reasons, and then turned around and wrote scary email to his friends anonymously.
She was not going to have the control over him she thought she could by thrusting herself into his life, his work, his religion. (his house...unannounced)
Everything just went down the proverbial toilet. I don't think sociopaths can be aligned with any religion in an honest way.. They may try to use them as tools to get something they want, or in their desire to morph into something again, for personal gain...