How was the Bible canonized? (idea)

• Apostlitic authority - that the authors were eyewitnesses to the fact, or else were followers of the apostles. See Are the gospels written by the people they're attributed to?
• Conformity - that the document was consistent with the church's practices and traditions. For example, this is why the Gospel of Thomas is rejected.
• Finally, general acceptance and usage of the church. Not only should the document be written by an authentic source and teach the correct teachings, it should be generally accepted that it was the divine word of God.

I think there is a lot of misconceptions as to how the Bible was canonized. It was not some sort of formulaic decision based on the criteria.

• Arthur Darby Nock, a professor at Harvard said to illustrate, "The most traveled roads in Europe are the best roads, that's why they're so heavily traveled."
• William Barclay said, "It is the simple truth to say that the New Testament books became cononical because no one could stop them doing so.
• Bruce Metzger, a professor at Princeton Theological Seminary gave the example: suppose a group got together today to pronounce the works of Bach and Beethoven as great music. We know it is, but not because of this pronouncement. It is great because of the merit of the music itself, and because we have a sensitivity as to what is good music and what is not.

  See also: Are the gospels reliable?