Author Bach claims to provide sympathetic, insider representations of a number of the smaller religious sects. While he does do so for Voodoism, Father Divine, the Oxford Movement, the Doukhobors, the Shakers, the Amanas, the Hutterites and the Mormons, he also treats what he calls 'the sex sects' (Baalism, Osirism, Shivaism etc.), particularly the non-Western and/or ancient with a broad brush indeed and without much evidence of especial expertise. Here it's more about supposed origins of the religious impulse and, I suspect, selling his book.
Bach is sympathetic indeed to the Western sects, particularly the Shakers, somewhat to the detriment of reportorial accuracy, especially as regards the Mormons. Personally, not having known much of them beforehand, I found his treatments of Father Divine, the Doukhobors, Shakers, Amanas and Hutterites interesting enough to make the effort of reading this book worthwhile.