Theology · Scripture, Tradition and the Magisterium

How Did the Church Decide Which Books Belong in the Bible?

A Book Without a Table of Contents

Every Bible begins with a list of contents. But nowhere in Scripture is there a passage that tells us which books belong in it. The list itself, called the canon of Scripture (from the Greek kanōn, a measuring rod), had to be recognised by the Church over time.

How did that happen? Which books were debated, and on what grounds were they accepted or rejected?

(For the specific question of the seven Old Testament books found in Catholic but not Protestant Bibles, see Why Do Catholics Have Seven More Books in the Bible?)

A Church Before a New Testament

The first Christians already had Scripture: the Jewish Scriptures, mostly read in the Greek translation called the Septuagint. When the New Testament speaks of “the Scriptures,” it means what Christians now call the Old Testament.

The writings that became the New Testament were produced over roughly fifty years, from the letters of St Paul in the 40s and 50s to the last Gospel near the end of the century. They were written to particular communities for particular needs. No one at first collected them into a single book.

But they were read aloud when Christians gathered for the Eucharist, alongside the Old Testament. By the early second century, St Ignatius, St Polycarp and others were quoting Paul’s letters and the Gospels with authority. The Second Letter of Peter already refers to Paul’s letters as being twisted by some “as they do the other scriptures” (2 Peter 3:16).

Pressure to Decide

Two challenges in the second century forced the Church to think more carefully about which writings were authoritative.

Marcion, a wealthy shipowner who came to Rome around 140, rejected the Old Testament entirely as the work of an inferior god. He produced his own canon: an edited version of Luke’s Gospel and ten of Paul’s letters, purged of anything Jewish. The Church rejected his truncated Bible and affirmed both Testaments.

The Gnostics produced many writings of their own, such as the Gospel of Thomas and the Gospel of Judas, claiming secret teachings of Jesus. The Church had to decide which writings truly came from the apostles.

The Four Gospels

By around 180, St Irenaeus of Lyons could insist that there were four Gospels, no more and no fewer: Matthew, Mark, Luke and John. He compared them to the four winds and the four living creatures of Ezekiel. The Muratorian Fragment, a list of New Testament books usually dated to the late second century, also accepts the four Gospels, Acts and most of Paul’s letters.

Notice that the four Gospels were never in real doubt in the mainstream Church. The later “lost gospels” were not suppressed rivals; they were later works that never won acceptance.

The Criteria

How did the Church tell an inspired book from others? Scholars generally identify several criteria the early Church used, often implicitly.

Apostolicity. Was the book written by an apostle or a close companion of the apostles? Mark was linked with Peter, Luke with Paul.

Orthodoxy. Did it agree with the “rule of faith,” the faith handed down in the churches founded by the apostles? A writing that contradicted the received faith could not be Scripture.

Catholicity. Was it accepted widely across the churches, not just in one region?

Liturgical use. Was it read publicly in the Church’s worship? The Eucharist was where Scripture was heard, and long use there was a strong sign of acceptance.

Underlying all of these was the conviction that the Holy Spirit guides the Church. The Church did not make these books inspired. She recognised the inspiration God had given them.

The Disputed Books

Most of the New Testament was accepted everywhere by the late second century. But a few books took longer. The historian Eusebius of Caesarea, writing around 325, called these the antilegomena, the “disputed” books:

Hebrews, because its author was uncertain (it does not name Paul);
James, 2 Peter, 2 and 3 John and Jude, short letters less widely known or quoted;
Revelation, accepted early in the West but questioned for a time in parts of the East.

Other writings, such as the Shepherd of Hermas and the Letter of Barnabas, were valued and sometimes read in church, but in the end were not accepted as Scripture.

The Canon Settles

In 367, St Athanasius of Alexandria, in his thirty-ninth Festal Letter, listed exactly the 27 books of today’s New Testament, the first surviving list to do so. He called them “the springs of salvation.”

In the West, the Councils of Hippo (393) and Carthage (397 and 419), and Pope St Innocent I (405), set out the full canon of both Testaments, including the deuterocanonical books of the Old Testament. From then on, the canon was settled in practice across the Church, though it was not solemnly defined by an ecumenical council until Florence (1442) and Trent (1546).

Reopened at the Reformation

The Reformation briefly reopened the question. Besides moving the deuterocanonical books of the Old Testament to an appendix, Martin Luther had doubts about four New Testament books: Hebrews, James, Jude and Revelation. He placed them at the end of his New Testament. He famously called James “an epistle of straw,” partly because of its teaching that justification is “not by faith alone” (James 2:24).

Later Protestants kept all 27 New Testament books. But the episode showed that without an authority to settle it, even the New Testament canon could be questioned.

What the Process Shows

The history of the canon raises a question that every Christian has to face. If the Church, through her bishops, councils and Tradition, could reliably recognise which books are inspired, then the Church has a real authority given by God. If she could not, then no Christian can be certain which books belong in the Bible.

The Catholic answer is that Scripture, Tradition and the Church belong together. The Catechism says: “It was by the apostolic Tradition that the Church discerned which writings are to be included in the list of the sacred books” (CCC 120). The Bible is the Church’s book, written within the Church, recognised by the Church and read in the Church, under the guidance of the same Holy Spirit who inspired it.