Unfortunately, just like rabid monkeys and Suze Orman, eventually it just gets scary and you feel like running away as fast as you can. When the book makes its way to talking about Mark David Chapman, it gets more ridiculous and I started to become angry with it.
The author begins his section on Chapman by collecting all the quotes he could find of people saying things like "I don't know what happened to the boy, he was always an angel" but then immediately starts detailing how completely insane he was. The problem is, he uses both as evidence of his being possessed by the devil. He was either a very normal person who suddenly killed a man (surely, it must have been the devil's work, then!) or he was an insane guy who rather predictably killed a man one day (surely, he must have been possessed!).
As Chapman goes through a thousand phases, alternating between good Christian who's a bit instable and raving lunatic who prays to Satan and reads The Catcher in the Rye like it was talking about him, Niezgoda uses both as evidence. "A great battle between good and evil was being fought over his body." No, when a man goes between explicitly insane and mentally instable, that's how crazy people are. If they were consistently crazy in front of other people, then they wouldn't be allowed to live on their own.
One large section of the book points out all the "nines" in Lennon's life through numerology, which doesn't really suggest to me that he made a deal with the devil in any way, but it's there. John and Yoko had a thing for numerology, and that likely caused several of the coincidences revolving around his later song titles and album release dates. Still, when the list consists of anything in John's life that had a 9 in it, or added its digits to make a 9, (1980 = 1 + 9 + 8 + 0 = 18 = 1 + 8 = 9. Come on.) or even if it had a 6 ("an inverted nine") you will eventually work up a huge list of numbers, unsurprisingly.
Directly after that, the book starts to talk about Finnegans Wake, James Joyce's thoroughly confusing work in half-English he worked on from 1922 all the way through 1939. This is perhaps the greatest leap of faith in the book (besides the whole Heaven/Hell God/Devil thing, which I suppose is a leap of faith for at least two-thirds of the world's population). First of all, Niezgoda lies that literary critics universally reject the work as either pretentious or stupid, then he suggests that Finnegans Wake is prophesying John Lennon's death at least forty years ahead of the murder and twenty years ahead of John making an alleged pact with the Devil. Here's a passage that he uses as evidence, with his emphasis included: