Is the Da Vinci Code true?
Was the Bible written by Constantine in 400 A.D.?
No. The Bible was written by the followers of Jesus from about 40 A.D. to about 120 A.D.. Bible verses are quoted as early as 95 A.D. by church fathers such as Clement of Rome. A number of very early Bible manuscripts have been found, the most significant being the Chester Beatty Papyrus, dated to 150 A.D., which contains portions from all four gospels and Acts. Obviously, these works were not composed 250 years later. The writings we now call the Bible began to be stored as a single collection in the late 2nd century, and people such as Irenaeus and Tatian started to defend it's authority as Scripture. By the 3rd century A.D, the Bible was essentially in it's current form and accepted by the vast majority of Christians. All that the Council of Nicea did was to reaffirm and formalise what had already been accepted as the Bible by Christians for centuries. Their debates were only over 2 or 3 disputed works.
Was Jesus married to Mary Magdelene?
No. There is no evidence for this claim. The text quoted by Dan Brown is misleading, because the actual manuscript is missing large portions of text from the passage he quotes, and. is dated to around 200 A.D.. The gospel accounts (dating to 50-90 A.D.) certainly do not portray Mary as anything more than a close friend of Jesus. The passage in John where Jesus says 'do not cling to me', or 'do not hold onto me' (John 20:17) is telling her that she should not get to attached to the risen Jesus, because he won't be around for long. The apostles were not harbouring ressentment towards the women; to the contrary, they held their women in much higher regard than did their culture. The fact that all four of the gospel writers chose to retain the embarrassing fact that Jesus was first seen by women, is proof of this. Women are also commended for their faith and work many times throughout the new testament by people other than Jesus. Genuine Christianity will not treat women as lesser beings than men (although this doesn't mean that their roles may differ at times).
Were there hundreds of 'alternative gospels'?
There were maybe a dozen or so, but most of these were written long after Jesus' lifetime, and had no credibility. Many of these were written by religious movements such as the Gnostics, who took Jesus' teachings and put a Gnostic spin on them. These works were largely ignored by Christians, who sought authoritative and trustworthy sources. This is evidenced by the way the Bible gained acceptance; some Biblical writings were accepted in their place of origin, but treated with suspicion in other geographic locations, where people were not aware of their authenticity. Over time, these people would accept the documents when they heard about the evidence for them. This is very different to the picture given by Dan Brown of a council imposing a canon against people's will. Intelligent people accepted the letters and gospel accounts which had evidence to back them up.
Was Jesus made 'divine' by the church?
It is true that at the Nicean Council, the there was a heated debate over the divinity of Jesus. Arius argued that Jesus, by virtue of being a human who obeyed God as Father, could not himself be God. However, Arius was challenging a strongly established belief, held by the vast majority of Christians, that Jesus was infact divine, and so his challenge failed, and his view became heretical. Everything from our early Bible manuscripts, to writings by the early church fathers, to comments by secular contemporaries such as Pliny the Younger, to early church creeds, indicate that Christians regarded Jesus as divine right from the beginning of the movement.