Here is my opinion. I say this as an Orthodox believer.
The Da Vinci Code was made as a scam so Mr. Brown can make some money. On the day his movie was released, 65 million dollars went into his bank account. Currently he is under allegations from the authors of Holy Blood, Holy Grail, Holy Bible. If you've read the book you can blatanly see that his date for the Priory of Zion is completely wrong. His facts page is nothing more than intrigue to atract people.
In 2003 he was interviewed by CNN when it newly came out. When they asked him if it was a fictional or factual book he replied, "If it was a fictional book it would read the same."
In 2006 recently when asked by 60 minutes on CBS the same question he replied, "Everything in this book is fact."
The books says fictional on it, yet he has a facts page. He also makes a claim that the Dead Sea Scrolls were founded in the 1950's. The truth is it was found in 1947. Now we see how Dan Brown can't get his dates right, he can't get his facts straight!
This guy is a class act.