Please keep in mind that nothing Dan Brown says in "The Da Vinci Code" can be taken as anything but complete fiction. He has based his story on the worst that pseudo history has to offer - rumors, myths and legends that have been kicked around for hundreds of years without any documentation or authentication - repetition alone has kept these stories alive. (I don't know about anyone else - but I am dubious of anything that will pass only the the examination of "It's been repeated often enough, it must be true!" - and will pass no other scrutiny at all. )
I don't, as many do, object to Brown's book on any religious grounds. I don't even really understand how any faith could be challenged by such a collection of misstatements. Any religion worth it's salt should be able to tolerate a bit of questioning. My objections to his book are that it is intellectually insulting - a combination of poor research, pseudo and outright bad history, and poor writing style.
All of the material used by Brown has been hashed and rehashed many times in recent years. The consipracy theories that he used were even used to some extent by Umberto Eco (a real author, historian and good writer of historical fiction). Much of Brown's premise comes from works like Lincoln, Leigh and Baigent's "Holy Blood, Holy Grail" and other similar fringe historical surveys. Brown is not a historian by any stretch of the imagination, and his claims to historical accuracy have all been thoroughly shot down - with a few exceptions:
- There were once Knights Templar
- Paris is a city in France
- London is a city in England
Outside of the above - take everything he says with a grain of salt. That's why they call it fiction - just like the Fairy Tales of Brother's Grimm, Gulliver's Travels and the Arabian Nights - someone made it all up. All of the above recite tales long told by others. At least the authors of the three works mentioned above didn't claim, as Brown did, that there was anything original included in their stories. Or anything true.