The Davinci Code is a book written by Dan Brown, though not using his own imagination. It is inspired by, and partially based on, two books written before his "work of art". It is a factually incorrect novel, put on the fiction shelf for a reason.
From the first page of the Davinci Code, you are hit with a lie wrapped in truth's clothing. Dan Brown creates this 'secret society' hidden by the Vatican, to be seen as a horrible and awful group. In truth, this secret society did exist - but not to commit crimes. Their goal was solely to help people in the way Christ would have wanted them to be helped, but in secret. They didn't want to make a name for themselves.
Second, you are lied to by having the "fact" that the Dead Sea Scrolls were found in 1950 and they contained secrets about Jesus, shoved down your throat. First of all, the Dead Sea Scrolls were found in 1947 and have NOTHING to do with texts called The Nag Hammadi (containing what is called the "Gnostic Gospels" by Dan Brown). Second, the Dead Sea Scrolls were written ONE HUNDRED YEARS BEFORE JESUS LIVED. How could these texts contain ANY information regarding Jesus' life?
Next, read the Nag Hammadi before you believe that they have anti-Christ-divinity writings in them. They only proclaim and renounce the divinity of Jesus, not denounce.
Also, the people who wrote these texts were BEFORE Constantine (the emperor who legalized Christianity). They were not of great influence - they risked their lives to share God's love.
Dan Brown wrote a good book. His facts were just very, very, very off. If he did his proper research, he wouldn't have even written the novel. It's too ridiculous when you sit to think about it.
The Davinci Code is a work of art, and fiction. Not a work of history, and truth.
The Davinci Code is less credible than Biblical Texts which it attempts to denounce and discredit.