The term canon comes from a Greek word meaning a reed or measuring stick. It is used today to refer to a list of authoritative writings. In the case of the Bible, we can really only speak of a canon of scripture when the list becomes fixed (i.e., no other books may be added or taken away).
The canon of scripture developed in both Judaism and Christianity over a long period of time before becoming fixed in the specific books included today by Jews and Christians. A three-fold process was involved in books coming to be considered canonical. First, a book was considered useful. Second, it was considered authoritative. Third, it was considered canonical (i.e., part of a fixed list).
For Protestants the Old Testament consists of 39 books. Catholics include 46 books in their canon of the scripture, including all of the books considered scriptural by Protestants plus several additional books or parts of books. Jews accept exactly the same books as Protestants (Martin Luther based his revision of the Catholic canon on Jewish practice), but they number the books differently, so that they only count 24 (or sometimes 22, to match the number of letters in the Hebrew alphabet, by combining Ruth with Judges and Lamentations with Jeremiah). Here is a chart of the Old Testament books.
| Protestant Grouping | Catholic Grouping | Jewish Grouping |
|---|---|---|
| Law (Pentateuch) | Law (Pentateuch) | Law (Torah) |
| Genesis | Genesis | Genesis |
| Exodus | Exodus | Exodus |
| Leviticus | Leviticus | Leviticus |
| Numbers | Numbers | Numbers |
| Deuteronomy | Deuteronomy | Deuteronomy |
| History | History | (Former) Prophets |
| Joshua | Joshua | Joshua |
| Judges | Judges | Judges |
| Ruth | Ruth | Samuel |
| 1 Samuel | 1 Samuel | Kings |
| 2 Samuel | 2 Samuel | (Latter) Prophets |
| 1 Kings | 1 Kings | Isaiah |
| 2 Kings | 2 Kings | Jeremiah |
| 1 Chronicles | 1 Chronicles | Ezekiel |
| 2 Chronicles | 2 Chronicles | The Book of the Twelve |
| Ezra | Ezra | |
| Nehemiah | Nehemiah | |
| Esther | Tobit | |
| Judith | ||
| Esther (+ additions) | ||
| 1 Maccabees | ||
| 2 Maccabees | ||
| Poetry | Poetry | Writings |
| Job | Job | Psalms |
| Psalms | Psalms | Job |
| Proverbs | Proverbs | Proverbs |
| Ecclesiastes | Ecclesiastes | Ruth |
| Song of Solomon | Song of Solomon | Song of Solomon |
| Wisdom of Solomon | Ecclesiastes | |
| Ecclesiasticus | Lamentations | |
| Esther | ||
| Daniel | ||
| Ezra-Nehemiah | ||
| Chronicles | ||
| Major Prophets | Major Prophets | |
| Isaiah | Isaiah | |
| Jeremiah | Jeremiah | |
| Lamentations | Lamentations | |
| Ezekiel | Baruch | |
| Daniel | Ezekiel | |
| Daniel (+ additions) | ||
| Minor Prophets | Minor Prophets | |
| Hosea | Hosea | |
| Joel | Joel | |
| Amos | Amos | |
| Obadiah | Obadiah | |
| Jonah | Jonah | |
| Micah | Micah | |
| Nahum | Nahum | |
| Habakkuk | Habakkuk | |
| Zephaniah | Zephaniah | |
| Haggai | Haggai | |
| Zechariah | Zechariah | |
| Malachi | Malachi |
Note that Jews group the books into three sections: the Law, the Prophets, and the Writings. The Law consists of the first five books, or the Pentateuch, and is traditionally ascribed to Moses. The Prophets may be divided into the Former Prophets (historical books) and the Latter Prophets (prophetic books), each consisting of four books. Jews consider Samuel and Kings to be one book apiece, and they group the twelve books Christians call Minor Prophets into a single book, the Book of the Twelve. Christians may be surprised at some of the books that are omitted from the Prophets section of the Jewish canon. The historical books of Chronicles, Ezra, Nehemiah, Esther, and Ruth, are not there, nor are the books of Lamentations or Daniel. All these books, plus Psalms, Job, Proverbs, Ecclesiastes, and the Song of Solomon, are placed in the Writings section.
The Jewish concept of canon began developing after their return from Babylonian exile in the 6th century B.C.E., but the canon was not absolutely established in its present form until the 2nd or 3rd century C.E. The destruction of the Temple in 70 C.E. and the expulsion of the Jews from Jerusalem in 135 C.E. spurred the development of the canon, although by that time the boundaries were almost fixed. The three sections--Law, Prophets, and Writings--were accepted as authoritative in the order presented. The Law was probably accepted as authoritative by the 4th century B.C.E., and the Greek translation called the Septuagint (LXX) was probably created in the 3rd century B.C.E., initially consisting only of the books of the Law. The Prophets were fixed in their present form and accepted as authoritative by the 2nd century B.C.E. The book of Sirach (also called Ecclesiasticus), written about 180 B.C.E., lists notable heroes of the Bible from the Law and Prophets, but the only one he mentions from the Writings section is Nehemiah. Most notably, he omits Daniel. Sirach's grandson, writing a prologue to his Greek translation of the book about 117 B.C.E., speaks of "the Law, the Prophets, and the others that followed them," suggesting that although the Law and the Prophets were fixed by this time, the Writings weren't. This view is confirmed by the New Testament, where Jesus speaks of "the Law, the Prophets, and the Psalms" (Luke 24:44). There is evidence that the Jews continued to discuss the authority of books like the Song of Solomon and Esther until perhaps the 2nd or 3rd century C.E. (The Samaritans, who permanently split from the Jews in about the 5th century B.C.E., accept only the Law as canonical.)
If the Jews fixed their canon of scripture by the 3rd century C.E. or so, Christians continued to debate which books in their Old Testament were authoritative. Since few Christians after the 2nd century read Hebrew, they read the Old Testament in Greek, and several additional Greek works of Jewish origin were available to them. When the Latin Vulgate was produced in the 5th century, it included Latin translations of several of these Greek works, over the objections of the principal translator, Jerome, who advocated an Old Testament that matched the books of the Jewish canon. His voice was a minority position, however, and his contemporary Augustine and others argued successfully for including books such as Tobit, Judith, Sirach, and the books of the Maccabees. These books continued to be used by most Christian writers throughout the Middle Ages, but it wasn't until Martin Luther advocated a return to the Jewish canon of the Old Testament that the Catholic church officially established the present list of Old Testament books used by the Roman Catholic Church at the Council of Trent in 1546. The Eastern Orthodox Church acted even later, accepting an Old Testament canon that was similar, though not identical, to the Catholic canon at the Council of Jerusalem in 1672. Protestants mostly followed Luther's recommendation to revert to the Jewish canon, though many (including Luther) continued to read the "apocrypha" and value it highly. Today, the term "apocrypha" is considered somewhat pejorative, so many Christians call the books deterocanonical instead (i.e., belonging to a second canon).
The canon of the New Testament had a separate and equally interesting development. Churches began copying and collecting the letters of Paul and perhaps one or two gospels, as they became available, in the late 1st and early 2nd centuries. Since many Christians of the first and second generations believed that Christ would return quickly, they felt no need for a fixed list of authoritative Christian books. By the middle of the 2nd century the situation had changed, both because of the perceived delay of the Parousia and because of historical developments within the church. A convert to Christianity named Marcion began to preach that the God of the Old Testament was a God of war, while the God of the New Testament, the father of Jesus, was a God of love, and the two were not the same. Marcion thus rejected the entire Old Testament, and he accepted as authoritative only the Gospel of Luke (in an abridged form) and ten of the letters of Paul (not including the Pastoral Epistles). Another Christian, Montanus, who lived at about the same time, began to teach that he and his female associates were in direct contact with the Holy Spirit and that their words had the authority of the written word found in the Law or the Gospels. Most Christians rejected the canon of Marcion as too restricted and the "canon" of Montanus as too broad, and prominent Christian leaders began to offer their opinions on which Christian books were authoritative.
As early Christians debated which books should be considered authoritative, a number of criteria appear to have been important:
The four gospels, Acts, and the thirteen letters of Paul were quickly adopted by the majority of Christians as authoritative. 1 Peter, 1 John, 2 John(?), and Jude were also widely accepted by the 3rd century, but Hebrews, Revelation, and a book called the Apocalypse of Peter were disputed. Other books which had brief local support, such as 1 Clement, the Didache, and the Shepherd of Hermas, were no longer in contention as authoritative books by the middle of the 3rd century, though they were still read. The books such as James, 2 Peter, and 3 John were largely unknown to most churches.
By the early 4th century, the churches in the eastern part of the Roman Empire accepted 21 books without question--the four gospels, Acts, fourteen letters of Paul (including Hebrews), 1 John, and 1 Peter--and they used the other six widely. In the West, 24 books, including Revelation, were generally accepted, and only Hebrews, James, and Jude were questioned. In 367 Athanasius, bishop of Alexandria, wrote a letter in which he listed the New Testament books he considered authoritative, and it is the first list that exactly matches our present New Testament (though the order of the books varies). Athanasius' opinion was not immediately accepted by the rest of the church, but gradually over the next century or two both the Eastern and the Western churches moved toward a 27-book canon. By the middle of the 5th century, the Western church firmly accepted all 27 books, though some Eastern churches still disputed Revelation, but by the year 600 the canon was settled throughout the majority of Christendom.
The modern New Testament canon is expressed in the following table. Note that the book of Hebrews is sometimes considered one of the Pauline letters (the traditional view) and sometimes one of the General or Catholic letters (the modern view). (Catholic letters means letters to the churches in general and is not named after the Roman Catholic Church.)
| New Testament Canon |
|---|
| Gospels |
| Matthew |
| Mark |
| Luke |
| John |
| History |
| Acts |
| Pauline Letters |
| Romans |
| 1 Corinthians |
| 2 Corinthians |
| Galatians |
| Ephesians |
| Philippians |
| Colossians |
| 1 Thessalonians |
| 2 Thessalonians |
| 1 Timothy |
| 2 Timothy |
| Titus |
| Philemon |
| (Hebrews) |
| General (or Catholic) Epistles |
| (Hebrews) |
| James |
| 1 Peter |
| 2 Peter |
| 1 John |
| 2 John |
| 3 John |
| Jude |
| Apocalyptic |
| Revelation |
An interesting exception to this description of the development of the Christian canon was the Syriac churches, which accepted a harmony of the gospels known as the Diatessaron, created by Tatian in the 2nd century, rather than the four separate gospels. It wasn't until the 5th century, under the influence of a certain forceful bishop name Rabbula, that the four separate gospels replaced the Diatessaron in most Syriac churches. The Syriac church also resisted the four minor catholic epistles (2 Peter, 2-3 John, Jude) and Revelation, so they had a 22-book canon for several centuries (they apparently also substituted a book called 3 Corinthians for Philemon). Eventually, under the influence of the churches to the West, the Syriac church moved in the direction of a 27-book canon, though the 22-book canon remained truer to their nationalistic feelings for some time.