The Bible as Christians know it today did not begin as one large volume-with Old and New Testaments. It came into being as part of a selection process called "canonization." The Greek word for "canon" can mean many things, such as "measuring rod" or "ruler." At first, the early church leaders used "canon" to mean a "standard," and later "a list" or "catalog" of authoritative writings. There were many books circulating among the churches throughout the Roman world that were read by the early church as Scripture. It was important for the church leaders at that time to go through a process of deciding which books were holy and had authority for God's people. This process did not happen overnight. It took hundreds of years for Jewish and Christian religious leaders and scholars to decide which of the many writings that were being read should be part of Holy Scripture, that is, the Bible.
The Hebrew Scriptures and the Old Testament
Chart examining the books in the Old Testament
Greek Versions of the Jewish Scriptures