The four gospels (known as the Tetramorph) were canonized ca. AD 160, but in wide use and acceptance along with the Pauline Epistles (Romans, Corinthian, etc) before the end of the First Century. Not written, the last of the books in the New Testament was written before the end of century, but canonized, mind you, as in, offically accepted. The New Testament was in its modern 27 book usage by AD 200. It was made official under the Roman government, newly Christian, at the Council of Carthage in 393, presided over by St. Augustine, who regarded the council as merely a formality, as the full Bible was already in circulation for over a century. The Council of Nicaea in 325 was the first sort of official Christian meeting after the Roman conversion, during which important other doctrines were made officicial, such as the date of Easter. So. I can see how that would be somewhat confusing, especially without Wikipedia lol.