Signal, password, and SOI are included as means of authentication in an opord. With the bible, the authentication was accomplished by the churches in possession of particular letters and gospels having the history of those letters as part of the history of those churches.
However, someone called those churches together into the councils that established the authentic books of the New Testament, in particular. That someone must have been a respected party.
I believe those early Christians maintained a connection and were not just random, isolated bodies of believers accidentally bumping into one another every now and then.
I believe that respected authority descended from the leaders of the Church in Jerusalem as seen in Chapter 15 of Acts.
Correct me if I’m in error...You are a retired Army chaplain?