Formation of the Canon
“…A written New Testament was not something the church formally ‘decided’ to have at some later date, but rather it was the natural outworking of the redemptive-historical function of the apostles. Inasmuch as that text was deemed to be an embodiment of the apostolic message, it would have retained the authority of the apostles and thereby the authority of Christ himself. It is here that we see the vivid contrast with the Bauer-influenced approaches noted above. Those approaches suggest that the writing down of these Jesus traditions took place before they were seen as authoritative (the latter happening at a much later date), whereas the historical evidence suggests that the traditions were seen as authoritative before they were written down (due to their apostolic connections).
Thus, it is not difficult to see why early Christians would have regarded some texts as authoritative from the very start. The idea of a New Testament canon was not something developed in the second century (or later) when the church was faced with pressing needs, but rather it was something that was handed down to and inherited by the early church from the beginning. It was the foundation for the church, not the consequence of the church. The idea of canon, therefore, does not belong formally in church history, but it is more accurately understood as a central plank in redemptive history.” - Andreas Kostenberger and Michael Kruger. The Heresy of Orthodoxy