Little is known for certain about the canonization of the Old Testament books. Opinions differ, but, generally, scholars think that the Old Testament was canonized in stages over several hundred years. The Torah was canonized first, probably in the 600s B.C.E.. The Prophets was canonized next, probably in the 200s B.C.E.. The Writings and the remaining books are thought to have been canonized in the 100s B.C.E. or the first century C.E.

When early Christians spoke of Scriptures, they were referring to the texts of the Hebrew Bible—the Old Testament. As Christians began to record accounts of Jesus’ life and teachings, and as Paul’s letters circulated to an ever-growing audience, a body of work that was completely Christian began to take shape.

For writings to appear in the final canon of the New Testament, church leaders decided that they had to meet certain criteria. First, the writings had to have widespread—not just regional—acceptance among the churches. Second, the writings must be connected to one of Jesus’ apostles by authorship or direct association. Third, the writings had to prove beneficial to the churches that heard them read. Fourth, the writings had to be deemed suitable for the reading public. In 397 C.E., church leaders met at the Council of Carthage and officially approved the twenty-seven books for the New Testament canon.