Yesterday I read The Intelligencer by Leslie Silbert. Earlier this summer, I read The Rule of Four by Ian Caldwell and Dustin Thomason. Last year, along with many of my fellow readers, I read The Da Vinci Code by Dan Brown. The three books have in common the theme of ancient secrets that could bring down religion/prove that someone didn't deserve the power they had/illuminate truths better hidden.
I've been thinking about the popularity of this genre, which is similar to Eco's The Name of the Rose but has the added twist of being more historical fiction than just plain fiction. The New Republic Online calls it Pop Esoterica! but I think that's too simplistic.
Years ago, I forget exactly when, someone said that as we (Americans) have gotten further from traditional religion and beliefs more and more people have started to believe in UFOs. Why? Because there's an atavistic need to believe in the "great other", someone or some thing or some power greater and outside human comprehension. Books like The Celestine Prophecy and the whole Erich von Daniken phenomenon become popular simply because they play to that need and have a veneer of "truth".
The fewer certainties we have, and religion did provide us with those ("Thou shalt/thou shalt not" leading to either a life with God or outside His presence), the more we search for them. Fundamental religions, esoteric beliefs (including Kabbala) and the search for life not of our world - this is the result of current cultural shifts. Where will this lead? Who knows. But those that believe that the aforementioned books are some form of truth are simply searching for some Greater Truth. Good luck to them.