The belief that the apostles wrote the New Testament is rooted in early Christian tradition, the content of the New Testament itself, and the writings of early Church Fathers. While the Bible does not explicitly document the process of its own composition, it provides us with clues and affirmations of apostolic authority and eyewitness testimony.

For instance, Peter refers to Paul’s writings as Scripture, acknowledging their divine authority alongside other sacred texts. In 2 Peter 3:15-16, he writes, “Bear in mind that our Lord’s patience means salvation, just as our dear brother Paul also wrote you with the wisdom that God gave him. He writes the same way in all his letters, speaking in them of these matters. His letters contain some things that are hard to understand, which ignorant and unstable people distort, as they do the other Scriptures, to their own destruction.” This passage suggests that Paul’s writings were considered authoritative and on par with the Old Testament Scriptures.

Moreover, many books of the New Testament are either attributed to apostles or to close companions of the apostles. For example, the Gospel of Matthew is traditionally attributed to Matthew, one of the twelve apostles, while the Gospel of Mark is said to have been written by John Mark, a companion of Peter. Similarly, the Gospel of Luke and the Acts of the Apostles are attributed to Luke, a companion of Paul, and the Gospel of John, as well as three epistles and the book of Revelation, are attributed to John, the beloved disciple.

The early Church Fathers, such as Irenaeus, Tertullian, and Clement of Alexandria, also provide testimony to the apostolic authorship of the New Testament documents. They often cited these texts in their own writings and defended their authenticity and apostolic origins against heretical teachings.

While modern scholarship may question the traditional attributions of some New Testament books, the early Christian community’s acceptance of these writings as authoritative and inspired, their consistency with apostolic teaching, and their widespread use in worship and doctrine underscore the belief that the apostles, either directly or through their close associates, played a significant role in the writing of the New Testament.