I gave this book 2 stars because it's fun to read -- much like many of the shows about aliens and the Masons, etc. are fun to watch. As a book about Gnosticism, however, it really doesn't deserve any stars. As the author points out, most Gnostic writings had been banned for centuries and copies of them had been destroyed. This led many people to speculate on the belief systems of the Gnostics -- basing thier views on the few references and fragments that were available. Of course, people tend to reflect their own views in their speculations. This author seems to be motivated or informed by such views.
Over the past 150 years, however, archeologists have uncovered many of the original Gnostic writings and we can, therefore, check our interpretations. (I find it interesting that the author quotes many books -- very often quoting the enemies of Gnosticism in the early church who were trying to argue that the Gnostics were heretics -- but rarely, if ever, quotes original source material of the Gnostics.) What the author presents can best be described as related to one strain of these wrtings (more or less in the way that the movie the Omen is related to Christianity). It seems to me that most of the ideas that he presents can be traced back to the Sethian tradition of the Gnostics -- which is by no means representative of all Gnostic thought. And, even his presentation of the Sethian tradition is highly interpretive and would be refuted outright by many of the Gnostic writings. It seems like the author -- or the author's sources -- are trying to use people's lack of understanding of Gnostic beliefs as a vehicle for presenting their own view of some kind of Luciferian religion -- one that would be wholly refuted by most of the Gnostic writings, and requires interpretation to find support in the Sethian tradition.
It's important to remember that you should be suspect of anyone who begins a sentence, "The Gnostics believed..." There are many Gnostic traditions and, if there is anything that truly unites them, it is the mystical idea that people can have a direct knowledge of/communion with the Godhead/the Absolute/the Uncreated. Since this knowledge is attained by individuals and is unmediated by church or doctrine, there is no one central authority. This has led to a wide variety of ideas. If you're interested in knowing what the Gnostics were thinking, I would suggest reading their own words. Many of the books are readily available. The Nag Hammadi Scriptures, found in Egypt, provide a great sampling of various strains of Gnostic thought and translations are available in a compilation with very informative commentary by actual experts