"Canon" is a term that refers to the rule of law used to decide whether a book measures up to a standard. In relation to the Bible, the canon refers to the identity of the collection of writings to be included in the Scriptures.
The canon of Scripture - What is it?
How were the writings included in our Bible determined? Three key principles have been observed over time. First, the writing had to take place through a recognized prophet, apostle, or someone associated with them. Second, their writing could not contradict a previous inspired Scripture. Third, the writings had to be widely accepted by the church and its leaders as inspired.
By the time of Jesus' coming to earth, all of the Old Testament had been written and accepted by the Jewish community. In the first century, the Old Testament existed in a list of 22 (or sometimes 24) books that included the same content as our current 39 books of the Old Testament. These writings were divided into the Law, Prophets, and Writings.
The New Testament includes 27 books that have been recognized as part of the canon of Scripture. Almost all of these books were noted as authoritative in the church from the earliest times (mid first century to early second century). The few exceptions include some of the shorter books that were not as widely circulated. However, by the mid third century, the full list of inspired writings was completely determined. It was during this time that the first existing complete New Testaments began to appear. In total, the church has affirmed 66 canonical books of the Bible.
The three tests of canonicity mentioned above were clearly confirmed for each book of the New Testament. Matthew, John, and Peter were each apostles who accounted for eight books (Matthew, John, 1-3 John, Revelation, 1-2 Peter). The apostle Paul accounted for 13 books. James and Jude, half-brothers of Jesus, each wrote one book. Luke, an associate of Paul, wrote Luke and Acts. Mark has been traditionally accepted as the teachings of the apostle Peter recorded by Mark. Hebrews, whose authorship is uncertain, is accepted as a book associated with Paul or an associate of Paul. In each case, authorship was connected to an apostle (or associate) or family member of Jesus and was widely accepted within the early church.
Later, the Roman Catholic Church (and some other groups) decided to include a collection of 14 books called the Apocrypha as part of its canon of Scripture. These books, written between the times of the Old and New Testament writings, first appeared with the Greek translation of the Old Testament called the Septuagint. However, the writings of the Apocrypha are not once cited in the New Testament, nor did Jesus affirm any of it when He recognized the Old Testament writings (Luke 24:27, 44).
The canon of Scripture was written early, determined early, and has been unchanged since those times. We can confidently accept the Bible today as God's Word, reading and living by its teachings that have been revealed and preserved for us today (2 Timothy 3:16-17).
What are the Catholic Apocrypha / Deuterocanonical books?
The Dead Sea Scrolls - What are they and why do they matter?
Were there different authors of the books of the Bible? Who were the authors?
How is the Bible inspired? What does it mean for the Bible to be inspired?
Are there errors in the Bible?
Truth about the Bible