Of course I didn't read it (not into Christian Thrillars myself) but many people accept this book as historical when it is fiction or at the very best, revisionist history.
I wouldn't classify The DaVinci Code or Angels and Demons to be "Christian Thrillers" at all. And while the story and the outcome are indeed ficitonal, what has capture the minds of so many is that the assumptions in the story are absolutely based in existing theological theory as well as having a solid historical basis.
What has captivated me about these two books are how very smart they are. If the subject matter were not theological in nature, I think Dan Brown's stories would likely still be great reads. They are like well crafted logic puzzles, and I found them delicious. I think they resonate so deeply because they have hit a nerve with the population at large who realizes that that history (and religious history in particular) is that which has been recorded and deemed accurate by those who wrote it down--and everyone has an agenda. To use solid, accepted history in conjunction with existing, seemingly fantastic, theories to tell a tale makes for an entertaining novel. They touch upon the fact that the world has started to grow beyond the doctrines and dictates of organized religion and the revisionist history that they have peddled to the masses for so long. It has sparked conversation and study and allowed many to form their own opinions about the nature of God and religion based on available information instead of the "that's just the way it is" party line. I appreciate that.
I find relicry and doctrinal formation fascinating, and these books were enormously fun for me to read. As a voracious reader, I rarely find books that I'm willing to reccomend so heartily as great entertainment reading. I devoured the pages and didn't know the ending by page 90--and that's saying something. I would even say that I enjoyed Angels and Demons even more than the DaVinci Code.