What we call the Old Testament was written by the Jews. It was accepted by the Jews and taught in synagogue. If it was in doubt as to being from God, it was left out. Interestingly, Jesus and all of the writers of the New Testament quoted from all books of the New Testament. They believed it to be accurate and inspired. As for what we call the New Testament, the last book of the New Testament (Revelation) was completed about 95AD. Many of the books were written by the time that the temple was destroyed in Jerusalem (70AD). What I'm getting at is that the books were written by the people who knew Jesus, who interviewed people who knew Jesus (Luke), or in Paul's case, he was alive at Jesus' time and met Jesus after His resurrection. They weren't conveniently "packaged together" like they are now. But the scrolls were copied and passed to the new churches that were springing up. There were plenty of eyewitnesses to His life. Anyone circulating "false scrolls" or books was immediately stopped and the book was immediately rejected because they knew that it wasn't true. One hundred to 150 years after the death of Christ the "gnostic gospels" started popping up (when there were no more eye witness.) People could see that what they were reading was at variance with what had been written already. These "gospels" were false ("gospels" of Philip and Judas for example). And they were not copied and circulated widely. Contrary to what a lot of people say, the Council of Nicea was NOT to decide which books belonged in the Bible. That had already been decided by the people of the early church who knew Jesus, or had heard the gospel from people who had known Him. IF the books had been inspired and true, there would be a lot more copies of those books in circulation. I also believe that God is in control. If He wanted certain books to be included, they would have been included no matter what anyone else thought or said. If He saw heresy slipping into the church, He would have kept those books out--no matter how many people tried to get them in. The "Apocalypse of Peter" would fall into this category.
