This book is a thriller/adventure book. Of course, that is my opinion. It is not a historical mystery or historical thriller. It is not a revelation on the true word of Christ; however, it is a small diatribe on the institution of the Catholic Church. Again, this is only my opinion.
My point being, if you like the thriller or adventure genres, then you might find this book to your liking. If you are considering this book because you find the history of the church or scriptures interesting, or you are looking to find a new, different view of the Bible, look elsewhere.
The story centers on a young priest, Ian Pearse, who gets caught up in a quest to find an ancient scroll. The Manicheans, a secret society of a Faith long thought destroyed by the Catholic Church, desperately want to find the scroll so that they may, in turn, destroy the Catholic Church with its revelations on the true word of Christ.
'The Book of Q' is, at points, far-fetched and contrived. But, hey, this IS fiction. My biggest complaint is the unnecessary detail Rabb uses in his descriptions of the various locales used in the book. Without providing maps to reference, his use of exact street names, as well as exact landmarks, often ends up being frustrating, and distracts from the story. Unless, of course, you have actually been to Vatican City and the other places described in the book.
Read this book for the adventure and suspense, not for theological extrapolations.