Upvote:1
It was written by the Church for the Church, to remind the Bishops what they should teach about Jesus to their new clergy. The New Testament is a sort of "Cliff notes," to the training program by Jesus. It was used to remind the Bishops what they had learned in "seminary." The teaching of Priests was through an apprenticeship program. The Bible was not used except to remind the Bishops what to do. It was written in obscure terms so that Gnostic churches could not understand the text and train their own priests in the methods of the Apostles. Jesus instructions on what to do to heal lepers, cure blindness, raise the dead, cast out demons etc. was not described. His mystical instructions were disguised in parables, that only the Church understood, and these understandings were only given to ordained clergy.
The Old Testament was included in the Bible to put down Gnostic teachings that God the Father was above Yahweh and Torah only applicable to Yahweh followers. Gnostic churches could not claim Apostolic connections and adopted Paul as their spiritual head. The OT gave the Church the tradition they needed to justify their position as the only true Church of Christ.
Upvote:6
Why not a potato gun?
Even before John died in Patmos there started to be other books which claimed to come from the Apostles or otherwise claimed to have been inspired by God. While in some cases this was not a terrible thing (some of them are quite dull, actually) others of these were wild departures from the teachings of Christ and were arguably destructive to the soul. As a response the Church started to gather together lists of what documents were known to have been of Apostolic origin. I believe the first such (or the first that we know about) list dates back to the end of the second century. It actually took the better part of three centuries for a genuine consensus to exist and when it was finally agreed upon that was more-or-less a gentleman's agreement: no ecumenical council decided the fact, everyone simply agreed.
It was over a millennium later that someone presented a serious challenge to the canon. One of the less talked about points which was a bi-product of the reformation was the fact that people started to call into question which books actually belonged in the Bible and which did not. In a response to this, the Council of Trent officially (and bindingly) defined the canon.
Among others:
What benefit is there to have a creed? What benefit is there in having a Catechism? One of the chief benefits of a canon is that it functions as a point of reference. You can deny Augustine, but you can't deny Paul.
It also served liturgical purposes. Even from the road to Emmaus, the Church has associated the breaking of the bread with the reading of scripture. Setting a defined list of scripture guarantees that what is read is something worth reading.
You may want to check out this article on the process.