I keep asking this question. Never get an answer.
We see with our own preconceptions. The early churches were encouraged to read the letters of the apostles and to trade their letters between them. Colossians 4:16, 1 Thessalonians 5:27, 1 Timothy 4:13, Revelation 1:3.
Even in the scriptures themselves, we see that the early churches had some of the new testament scriptures already.
Now if you believe the present Roman Catholic Church has the same authority as the apostles, then no additional verses I show will mean anything. But consider the qualification for inclusion into the Bible canon. One qualification was that the book had to be written by a apostles or a direct student. If full authority passed from apostles to the next generation of apostles, why was this limitation imposed?
2 Thessalonians 2:15 So then, brothers, stand firm and hold to the traditions that you were taught by us, either by our spoken word or by our letter.
Galatians 1:9 As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed.
Now with your preconceptions, if the current Roman Catholic Church has apostolic teaching authority, then neither of the above verses mean anything. But if we are to stand firm in the apostolic teaching, why did the creators of the canon limit the apostolic scriptures to the writings of the apostles and their direct students?
Where did Christ say His Church would be based on a book? Or a collection of letters?