Why Bibles Differ – Canon and History
One of the most common questions people ask when exploring the Bible is: Why do some Bibles have different books? The answer lies in the history of how the Bible was formed and transmitted, especially in the early centuries of the Church.
While all Christian traditions agree on the core content of the Bible—especially the New Testament—there are some differences in the Old Testament canon, based on the particular textual traditions and liturgical practices that shaped the churches of the East and the West.
The Old Testament and the Septuagint
Before the time of Christ, Jewish communities in the Greek-speaking world translated their Scriptures into Greek. This translation, known as the Septuagint (LXX), included not only the books found in the later standardized Hebrew canon, but also several additional writings—books like Wisdom, Sirach, Baruch, Tobit, Judith, and 1 & 2 Maccabees.
The early Church, which spread rapidly throughout the Greek-speaking world, adopted the Septuagint as its primary version of the Old Testament. This is the version most frequently quoted by the New Testament authors themselves. As a result, the Septuagint-based canon became the standard in both Eastern and Western Christianity.
Later, in the first centuries after Christ, most Jewish communities narrowed their canon to what is now called the Masoretic Text, a more limited Hebrew version. While this text became authoritative in most of Judaism, the Church continued to use the fuller canon received through the Septuagint.
Until the 20th century, Western (Roman) Catholic versions of the Old Testament were translated primarily from the Latin Vulgate, rather than from the Septuagint or the Masoretic Text. The Vulgate itself was based on a combination of sources, including the Septuagint, a pre-Masoretic Hebrew text, and the Old Latin versions. In 1943, Pope Pius XII issued the encyclical Divino Afflante Spiritu, which directed that translations of the Holy Scriptures should henceforth be made not from the Latin, but from the original language texts. As a result, modern Western Catholic translations began using the Masoretic Text as the base for the Old Testament—yet often still incorporate and compare it with the Septuagint, recognizing its historical and theological importance.
Catholic, Orthodox, and Protestant Canons
By the fourth century, the Church had largely settled on the canon of Scripture used in worship and teaching, including the fuller Septuagint tradition of the Old Testament. This canon was reaffirmed at later councils—both in the East and in the West.
During the Protestant Reformation in the 16th century, Reformers chose to align the Old Testament with the shorter Masoretic Text, removing the so-called “Deuterocanonical” books from their Bibles. These are the books still present in Catholic and Orthodox Bibles but absent from most Protestant editions.
The Catholic Bible includes 46 Old Testament books and 27 New Testament books, for a total of 73.
The Orthodox Bible includes a similar core, but may include up to 49 Old Testament books, depending on the particular tradition. Most Eastern Catholic Churches have the same biblical texts as their corresponding Orthodox Churches.
The Protestant Bible typically includes 39 Old Testament books and 27 New Testament books, for a total of 66.
Though the number of books may differ, all Christian traditions affirm the New Testament in its entirety. These variations in the Old Testament canon do not affect the core of the Christian faith, as the Church has always given primacy to the Gospels, followed by the rest of the New Testament, and then the Old Testament writings as a whole.
“The sacred and inspired Scriptures are sufficient to declare the truth.”
—St. Athanasius
One Faith, One Story
The differences in the biblical canon do not divide the core of the Christian faith. All Christians revere the Bible as the Word of God and look to it for guidance, truth, and salvation.
The Church, in both East and West, continues to read the Scriptures as a unified story of God's love—from creation, to the covenant with Israel, to the fulfillment in Jesus Christ and the life of the Church.
The different canons reflect historical developments, linguistic contexts, and liturgical needs—but they do not change the essential message of salvation. The Bible remains, in every tradition, a gift from the Holy Spirit and a treasure of the Church.
“Continue in what you have learned and firmly believed, knowing from whom you learned it, and how from childhood you have known the sacred writings that are able to instruct you for salvation through faith in Christ Jesus.”
—2 Timothy 3:14–15
Part 7 – Which Bible Should I Read? →