His message was more than the sermon on the mount. It is who He is and was, his relationship with the divine, and who we are and our relationship to the divine.
The DaVinci Code and its forebearers are gnostic follow-ons. They hold completely different teachings on the nature of Jesus and completely differnt teachings on who and what and how he taught.
They teach that Jesus's "true" teachings were suppressed by a conspiracy; that what Christians believe today is a result of that conspiracy.
In short: whether Jesus was married to St. Mary M. is a tiny part of the problem.
Another phase of the on-going Enlightenment project to discredit Christianity. The"illumanti" are so caught up in that that they will promote the most fanciful notions. If they read, say, the Gospel of John they would know that Jesus was not primarily a "teacher " or even as a healer, nor as a public personality was he different from other charismatical figures of the time, the best know of whom was John the Baptist. What distinguished him was the events of Holy Week. Christianity, as the Holy Father has pointed out, is not about words, but about the Word, about the events. He is remarkable not for what he said, but what he did.