Do we have the right books in our New Testament? That question is raised by The Da Vinci Code and other works that attempt to redefine Jesus. The issue is the canon. The word, canon, literally refers to a rod used in measuring and became a term used for which books belong in the Bible. The process of recognizing which books belong was called canonization.
Inspired writings (2 Timothy 3:16-17, 2 Peter 1:20-21) were authoritative the moment they were written. It is better to see the canon as a collection of authoritative books than as an authoritative collection of books. The authority adhered in the writings themselves.
The need to recognize which books were inspired arose from the threats of heresy and persecution and the practical issue surrounding the availability of the codex (or book format) which allowed many writings to be bound into one. Christians needed to know which books came from heretics, which books they were willing to die for, and which books should be bound together in a codex.
Three criteria were used by early Christians. Apostolicity asked whether a book came from an apostle or a close associate of an apostle. The writing would also have to be old enough to come from the apostolic period. Orthodoxy raised the question of whether the writing was consistent with the apostolic message and the Old Testament. Catholicity (which means universality) was a test of whether the churches everywhere received the writing.
The first person to write a canon list was Marcion, a second century heretic (c. A.D. 140). His included an edited version of Luke and edited versions of 10 of Paul’s letters. Marcion rejected all things Jewish and rejected the God of the Old Testament. Given the current interest in Gnostic gospels, it is interesting to ask why didn’t Marcion list those other gospels? The answer is they hadn’t been written yet or Marcion knew that no one would take them as authoritative. Despite the assertions of The Da Vinci Code, the other gospels were not serious contenders for the canon.
The Muratonian Canon is a list that dates from the latter part of the second century. Unfortunately, it is also fragmentary. It lists the four gospels, Acts, 13 letters of Paul, Jude, Revelation, 1 John, and either 2 John or 3 John or both. Clearly there was undisputed support for the bulk of our New Testament in the second century.
The only New Testament books that were ever disputed were Hebrews, James, 2 Peter, 2 John, 3 John, Jude, and Revelation. Slowly over time the early church answered its questions about these. A consensus of a 27 book New Testament arose by the fourth century. But more importantly, never were there more than four gospels or the 27 books of our New Testament considered undisputedly as a part of the canon.