This book was instrumental in making sense of the craziness that is the Mormon church (AKA The Church of Jesus Christ of Latter-day Saints). All the historical anachronisms, all the blatant plagiarism from the Bible, the incorrect prophecies of Joseph Smith, the way he "married" upward of 30 women (some of them as young as 14 years old), his history as a treasure-digging con man - all that is brought to light in the CES Letter book.
Anyone who is Mormon and has ever thought, "Am I crazy, or does some of this stuff in the Mormon church make no sense?" needs to read this book. Spoiler: you're not crazy, you're just beginning to be aware of how crazy the Mormon church is. Take the red pill, and see how far the rabbit hole goes.