The differences between the Catholic and Protestant bibles took shape in the 4th century AD with a disagreement between two early saints. St. Jerome saw the Hebrew translation of the Old Testament as the inspired word of God, while St. Augustine accepted a later Greek translation as God’s word. The early Catholic church embraced St. Augustine’s argument; however, centuries later, Protestants would side with St. Jerome, creating key disparities between Catholic and Protestant texts.
The original Hebrew Old Testament includes 39 books. But in approximately 200 BC, when Hebrew scholars translated the bible into Greek, the texts expanded to include 46 books. Hellenistic Jews used this translation, called the Septuagint, as did many early Christians.
In approximately 382 AD, the ascetic St. Jerome decided to translate the original Hebrew bible into Latin. During this process, St. Jerome became convinced that the Septuagint included inauthentic books. Another ascetic and one of the period’s most prolific scholars, St. Augustine, began writing to Jerome and defending the holiness of the Greek translation. The two saints never reached an agreement and neither did their successors.
Catholics have continued to embrace the Greek translation as their official bible. The Catholic bible has 46 Old Testament books. This includes seven books that did not appear in the original Hebrew: Tobit, Judith, First and Second Maccabees, Wisdom, Sirach (Ecclesiasticus) and Baruch. In the Catholic Bible, the books of Esther and Daniel also have extra passages. The Catholics refer to these additions as "deuterocanonical," which means of the second canon.
When Martin Luther broke with the Catholic Church in the 16th century, he embraced St. Jerome’s argument and returned to the original Hebrew. His Protestant contemporaries, most notably John Calvin, did likewise. The Protestants acknowledge 39 Old Testament books and refer to the extra seven Catholic books as “Apocrypha,” which means hidden. While some Protestant bibles do include the Apocrypha, they treat the additional texts as an unequal addendum to the God-inspired texts. The Protestant New Testament, like the Catholic version, contains 27 books and has caused few disagreements.
Even if the technical disparities between Catholic and Protestant bibles seem minor, they have had major effects. For example, 2nd Maccabees, a book that appears only in the Catholic Old Testament, introduces purgatory and the practice of praying for the dead. Most Protestants deny that purgatory exists and believe human prayer cannot influence the souls of the deceased. Another Catholic book, Tobit, emphasizes the importance of doing good works to please God. The Protestants, however, believe that God’s grace, regardless of peoples’ works, leads to eternal life.