First of all: excellent writing. Honestly. Strong line-by-line articulation of ideas.
The first half of the book is Anton LaVey's background and it's honestly fascinating. His childhood, years in the carnival and early exploits are genuinely fun. He lived 10 lives before he was 40. Of course, almost everything is entirely fabricated and has been debunked. So treat it as pure fiction.
The second half was written while LaVey was still alive but after the point he became a recluse. It's mostly him spouting off on his sexist, racist, old-man-yells-at-sky bullshit. It goes on for a shocking length, and frankly I skipped entire passages.
Recommended as a manufactured historical artifact, but not a moral compass, and that has absolutely nothing to do with religion.