From a reviewer writing for amazon.com:
The Da Vinci Code by Dan Brown is a gripping mystery novel. The story moves on four fronts: the hero and heroine, the head of a Roman Catholic organization, the chief inspector of the French police and a fanatical murderer. Like checkers on a checkerboard the chapters move these pieces of the story in turn until they all reach home row at the end. The author is able to maintain suspense throughout the story so that it has momentum to the very last page, not letting the mystery completely dissolve until the end. It is not the nature of this book to probe deeply into the human character, the nature of reality or to generate beautiful prose. It reads like a movie script, al la Raiders of the Lost Ark.
The author uses two characters as experts on everything, especially Christianity and some of its historical struggles. Because the book is fiction it is able to build its own picture of Christianity and the church without regard to historical accuracy. It does convey a patronizing attitude toward the church and its faith, an attitude common place now and throughout the history of the church.
Theirs is an old scenario: Jesus was a great man whose movement got hijacked by powerful people in Roman society and transformed into a secular power. Their version adds the proposition that Jesus was married to Mary Magdalene and the two produced children. This story line sets up a classic mystery novel struggle between an evil titan and a heroic minority replete with centuries of intrigue and violence, i.e. Luke Skywalker and the Federation. This is all great fun in a novel, but should not be confused with the truth.
Proposing that Jesus was married and had children is just another way of saying he wasn't the one proclaimed by the Christian faith, that he was a man in the flow of history not an intersect between God and history. Tying this idea in with the worship of a female goddess adds mystery and tension to the story and taps into the energy of the modern struggle between the sexes and society's effort to harness the sex drive.
Genuine historians that are anti-Christian don't claim that Rome hijacked the Christian movement, but rather that the Christian movement hijacked Rome. So even though the church was changed by its being adopted as the state religion, and even though its secular power led to terrible corruption, it's first three hundred years laid down the fundamental message. Constantine did not. What he did do was demand that the church settle its message so he could have a coherent religion to authorize.
The story line of this book elevates the divine female as if this were a breath of fresh air in an oppressive male-dominant Christian society. The divine female is nothing more than the ancient worship of sex. It is as commonplace as Hustler magazine. The worship of Venus three thousand years ago is the same impulse that drives the advertising and entertainment industry today. Just as commerce is dependent on sex today, production was linked to procreation then. If you could get the male and female gods to mate (so they reasoned), you could produce human, animal and vegetable crops on the earthly plane, i.e. wealth.
Christianity was born into a male-dominated culture. It didn't create it. The church has deviated from its earliest affirmation of the equality of male and female ("in Christ there is neither male nor female" -- the apostle Paul, 60 AD.) God's voice in the Bible never admits to being male or female. When Moses asks for God's identity, he gets "I am who I am."
The book's experts are fiction and so is their expertise. Solomon's temple, for instance, was destroyed long before Mary Magdalene came along. We know little about it and certainly don't know what its columns looked like. It was the second temple, the one build by Herod the Great that she would have seen. The holy of holies was not under ground but rather stood at the center of temple mount. She couldn't have gotten in it much less under it, dead or alive. The Crusades were a silly business that brought back nothing of historical value except the knowledge of a Muslim culture more advanced than the European culture. The Crusaders were completely ignorant of the land they conquered. The local people neither new nor cared where the bones of Mary Magdalene might be. They did know they could sell the Crusaders anything with the right story. So the knights credulously or greedily brought back relics purported to be fragments of the cross, the hair of John the Baptist and so on. The grail may have had a forged artifact initially or may have just been a story brought back without the souvenir.
My expertise doesn't extend to all the areas the "experts" in the book claim, but if their errors in fact are consistent with the ones I can pick out without research, I presume that it is all fiction and should be taken as such.
It is a fun book that is irrelevant to the serious subjects of Christian faith, sexuality and hope for a better world.