How do you figure that there was no NT for 300 years? The NT was written by the first generation of Yeshua's (Jesus') followers. They were recognized immediately by Yeshua's followers, being quoted as authoritative by the early Church fathers from the very beginning.
The Catholic Church eventually declared that the books of the NT were all the Word of God. Prior to that they were just books that had good teaching in them.
Is that you, Dan Brown?
Dan Brown,
Please read some acurate history of the Church.
The NT was not declared to be so until the 300s.
NO ONE disputes this historial fact.
What planet are you from?