My research finally led me to the origin of the New Testament.
It was at the Third Synod of Carthage in 397.
http://www.ntcanon.org/Carthage.canon.shtml
The books were represented in a letter by Athanasius because
each writing had three qualifications:
1. apastolic authority - ie written by one of the members of Jesus'
immediate community
2. support of a major Christian community
3. an absence of false teachings - ie. the book hadn't been edited
or modified. All other writings were discarded as heretical.
That, in essence, codified the teachings of Christianity to this day.
How did the members of the early Christian community maintain
its unique identity until 397? By custom and tradition.
That's the reason why I question those that deny tradition and only
rely upon the New Testament for their authority. The written word
only became authority 369 years after the crucifixion.
To those that quote scripture for their authority I respond: You
don't have a clue of the meaning, history and import of Christianity.
I get so weary when people quote scripture alone as authority
for their views on any ethical issue.
Historica footnote: St. Augustine of Hippo wrote in the early 400s.
The reference indicates he attended the Synod along with Jerome who
translated the Greek writings into Latin. For Hippo is in the region
of Carthage.