Recently a lady at church asked me about the Da Vinci Code. One of her relatives had criticised her Christian faith by referencing The Da Vinci Code. In one since he was using a fictional account to attack the Christian faith.
Christian History magazine did a good write up on the Da Vinci Code from the point of view of history. I highly recommend their article.
The organzization Answers In Genisis gives a good answer on the formation of the Bible in relation to the Da Vinci Code.
The Tekton site has a review of the Da Vinci Code but is a little involved.
So that is three different approaches to answering the novel.