Development of the New Testament canon

The canon of the New Testament is the set of books many modern Christians regard as divinely inspired and constituting the New Testament of the Christian Bible. For most churches, the canon is an agreed-upon list of 27 books^[1] that includes the canonical Gospels, Acts, letters attributed to various apostles, and Revelation.

The development of the New Testament canon was a gradual process that unfolded over the first few centuries of Christianity. Initially, texts were valued based on their connection to the apostles or their close associates rather than on explicit claims of divine inspiration. Early Christian communities circulated various writings, including the Pauline epistles and gospel accounts, without a universally recognized canon. Figures like Clement of Rome, Justin Martyr, and Irenaeus referenced and sometimes quoted these texts, but their status as “Scripture” was often informal, and debates persisted over which writings were authoritative. Marcion of Sinope, in the mid-2nd century, was the first to propose a clearly defined canon, excluding the Old Testament entirely and selecting only a version of Luke and ten Pauline letters, which prompted proto-orthodox Christians to define their own broader collection.

By the 4th and 5th centuries, the canon became more formalized through regional councils and ecclesiastical authorities. Athanasius of Alexandria, in his 367 Easter letter, listed the same 27 books that would later constitute the modern New Testament, using the term “canonized.” This list was affirmed by the Synod of Hippo (393) and the Councils of Carthage (397, 419) under St. Augustine’s authority. The Western Church, under Pope Damasus I and later Pope Innocent I, solidified this canon, and the Latin Vulgate commissioned by Damasus around 383 helped fix the text in the West. By the 5th century, the Eastern Church largely agreed, including the Book of Revelation, establishing widespread acceptance of the 27-book New Testament across both Western and Eastern Christianity.

Variations persisted in certain regions and traditions, particularly outside the Roman Empire. Syriac, Armenian, Coptic, and Ethiopian churches exhibited minor differences in the books they accepted, reflecting gradations in perceived spiritual authority rather than outright rejection. The Syriac Peshitta, for example, originally excluded 2 Peter, 2 John, 3 John, Jude, and Revelation, maintaining a 22-book New Testament canon. Full dogmatic articulations, such as the Council of Trent (1546) for Catholics, the Thirty-Nine Articles (1563) for the Church of England, and the Synod of Jerusalem (1672) for the Greek Orthodox, eventually codified the New Testament canon definitively, cementing the 27-book standard recognized by most Christian denominations today.