The earliest gospel was Mark, a mere 80 years after Christ.
BUT we have fragments of Mark in letters to and from the various churches from far earlier. A complete gospel of Mark is can be put together from these letters a mere 40 years after Christ. AND fragments exist even earlier.
So the early Christians did NOT rely on “tradition.” they had the Gospel. That is history my friend, not tradition.
My source: Evidence That Demands a Verdict, by Josh McDowell. He was an atheist that set out to prove the bible wrong. He ended up converting when the truth could not be ignored.
Now its your turn, show me scripture.
Do you think EVERY Christian in the year 80 had their own printed bible? How many were there? How many people had their own?
I’d be willing to guess. .000000000001 percent? 1 out of 5 million?