This book came my way during a period of willful rebellion against God. In a way, I am very Jacob like in my relation to God -- we wrestle quite frequently; He has proven Himself to be most forgiving. (It goes like this: J gets KO'd. God says: Have you had enough yet or do you wanna go for another round? And I'm like, yes we will, until you answer my question!)
What is important about this book -- besides the impeccable scholarship -- is primarily its unique aggregation of highly esoteric, forgotten, and repressed facts about the evolution and dynamics of spiritual thought among the ancients and the direct impact of these fluxes on our contemporary societies. My personal interest was and remains the first 1/2 of the book; I have little interest in declared purpose of book, which is an investigation into the "Great Heresy" (which is for the 'high-minded' da vinci code set).
It is possible that the book is a difficult pill, whether due to challenges is presents to preconceived/given 'narratives' (if you are a believer in one of the monotheistic faiths), or simply due to a lack of familiarity with the broader historic currents and personalities that are investigated in this book. Nevertheless, I believe your understanding will be enriched.
Highly recommended. 4+1/12 stars