Jesus and his disciples spoke Aramaic and used the Hebrew version of the Jewish Scriptures, but the apostle Paul and many other early Christians spoke Greek and used the Greek version of the Jewish Scriptures (Septuagint). Of the many Old Testament passages quoted or referred to in the New Testament, most are taken from the Septuagint. Though a small number of Christians, by the third and fourth centuries, thought that the Jewish Scriptures should not be part of the Christian Bible, most believed, as did the writers of the New Testament, that the Jewish Scriptures were the Word of God. They considered these writings as holy and authoritative, and as suitable for instructing Christians about God and faith (Mark 7.13; Rom 3.2; 2 Tim 3.16; Heb 1.1).

After all, they would have argued, Jesus said that he did not come to do away with the Law and the Prophets, but to give them their full meaning (Matt 5.17-19). The twenty-seven books that are included in the present New Testament were written by a number of different authors, the earliest ones being written as early as A.D. 50 and none being written any later than the early part of the first century. Exact dating is not possible, but certain books give clues about when they may have been written. The letters of Paul are probably the oldest writings included in the New Testament. Matthew, Mark, Luke, and John (the Gospels) were probably written between A.D. 60, ten years before the temple was destroyed in Jerusalem, and A.D. 100. Most scholars agree that Mark was probably the first Gospel written, since Matthew and Luke seem to take many of their details and the order of events directly from Mark. Some of the other letters and Revelation were probably some of the last books to be written, since they seem to give a picture of the situations Christians faced at the end of the first century and in the early part of the second century A.D. See the Introductions to each New Testament book for explanations of when they might have been written. The books included in the present New Testament were not the only letters or Gospels written by Christians during the first and second centuries. It took many years of debate between church leaders and scholars to finally settle on an accepted list (canon) of New Testament books. Various church leaders proposed different lists in the three hundred years that followed the writing of the New Testament books, but the list proposed in A.D. 367 by a bishop of Alexandria named Athanasius is the accepted list that nearly all Christian traditions accept today. How did the church leaders decide which books should become part of the accepted list? There were probably three "tests" they used to make their decision. First of all, a book had to have some connection with one of the early apostles. This meant that either the apostle was judged to be the writer of the book, or the material was thought to capture the key teachings of that apostle. Second, the book or letter had to be in agreement with the Jewish Scriptures and other accepted New Testament writings. The third test had to do with usage. Was the book or letter accepted and being used by a majority of Christians? If so, the case for including it as part of the New Testament was stronger. The Protestant, Roman Catholic, and Eastern Orthodox churches all generally consider the twenty-seven books of the New Testament to be "canonical" and usually list them in the same order in their Bibles.