When Christians speak of the canon of Scripture, they mean the list of books recognised as part of the Bible. Why does the Bible contain these 66 books and not others? Who decided? This article explains the idea simply.
What does "canon" mean?
The word comes from the Greek kanōn, meaning a measuring rod or rule. Over time it came to mean a standard — and then the list of books that serve as the standard for Christian faith and life.
The Old Testament canon
The books of the Old Testament were recognised by the Jewish people as sacred long before the time of Jesus. The Hebrew Bible is traditionally arranged in three sections:
- The Law (Torah) — the five books of Moses.
- The Prophets (Nevi'im) — including historical books such as Joshua and Kings, as well as Isaiah, Jeremiah, Ezekiel and the twelve shorter prophets.
- The Writings (Ketuvim) — including Psalms, Proverbs, Job, Daniel and Chronicles.
Jesus himself referred to this threefold collection when he spoke of "the law of Moses, and in the prophets, and in the psalms" (Luke 24:44, KJV). The New Testament writers quote the Old Testament frequently as Scripture.
The Protestant Old Testament contains the same books as the Hebrew Bible, arranged into 39 books.
The New Testament canon
The New Testament books were written in the first century. Early Christians quickly began to read the Gospels and the apostles' letters alongside the Old Testament in worship. Even within the New Testament, Peter refers to Paul's letters as Scripture (2 Peter 3:15–16).
Over the next few centuries, churches across the Roman world gradually recognised which writings carried apostolic authority. Some books, such as the four Gospels and Paul's letters, were accepted very early and almost everywhere. A few, such as Hebrews, James, 2 Peter and Revelation, were discussed for longer before being widely accepted.
In AD 367, Athanasius, bishop of Alexandria, listed the 27 books of our New Testament in a letter to churches. Church councils at Hippo (393) and Carthage (397) later affirmed the same list.
How were books recognised?
Early Christians looked for several marks:
- Apostolic connection — Was the book written by an apostle or a close associate of an apostle (for example, Mark with Peter, Luke with Paul)?
- Faithful teaching — Did it agree with the message of Jesus and the apostles, and with the rest of Scripture?
- Widespread use — Was it read and valued by churches in many regions, not just one?
- Spiritual power — Did it bear the marks of God's Word, building up faith and holy living?
Recognised, not invented
An important point: the church did not make certain books Scripture by voting on them. Rather, Christians recognised the books that already carried God's authority. The lists and councils confirmed what churches had long been reading and trusting.
What about other ancient books?
Many other religious writings circulated in the early centuries. Some were helpful but not considered Scripture (for example, early church letters such as 1 Clement). Others, often called "lost gospels" — such as the Gospel of Thomas — were written later and taught ideas that differ from the apostles' message, and so were not accepted.
Different canons today
Protestant Bibles contain 66 books. Catholic and Orthodox Bibles include several additional Old Testament books, sometimes called the deuterocanonical books. See what is the Apocrypha? for more.
Why it matters
The canon gives Christians confidence about where to find God's Word. It sets the boundaries for faith, teaching and worship, and it reminds us that the Bible is not just a collection of religious ideas but a trusted standard handed down through the centuries.
Continue with how the Bible was preserved.