I finished the Da Vinci Code. I had been asked by a few people if I had read it. They're familiar with my spiritual journey and know that some of what Dan Brown wrote mirrored some of what I have said in the past.
Spiritually, I only know/believe one thing these days: God exists. I don't know what God is or what God is all about or how involved God is in our lives, but there is too much order in the universe to deny intelligent design. Anyone who can do that can do, well, whatever they like. I just can't believe that my 4-pound brain can grasp the nature of that being.
If others know the truth more authoratatively than I do and believe more confidently, I envy them. I don't personally assert my questions and doubts upon others unless pointedly asked. In a conversation, I'm more inclined to tell a Christian supportive chapter and verse than anything else.
That said, here are my thoughts on the Da Vinci Code...
Obviously, Mr. Brown spent a lot of time reseaching and creating the plot and puzzles. The facts that he cites of early church history are pretty close to what I know to be true. My understanding from several sources is that Constantine's Council of Nicea was a political, not a spiritual, event. Afterward, his government killed people who believed other than what was declared to be true and so history and doctrine were cemented for centuries.
Dan Brown is also right that there are a plethora of other gospels than just Matthew, Mark, Luke, and John. Thomas, Philip, and so on all wrote about their experiences. But these weren't included in what we know as the Bible. Why? Beats me, but the committee didn't want to include them.
The whole Jesus married Mary thing... I don't know. For my spiritual life, it doesn't matter. I don't think I'll research it further for that reason.
But any book that causes churches to fight it as hard as they do, well that's just great marketing. Just as people were fighting Mel Gibson for his pretty much straight-from-the-bible film, Passion, which helped boost the buzz around it. (Great film, by the way. Very accurate to the text of the bible, which is partially why it sold as well as it did.)
Great book, but it's just a book. It shouldn't determine faith.