Papias (fl. ca. 125-150), an early bishop of Hierapolis, mentions Mark and Matthew in what the church historian Eusebius (ca. 325 CE) says is a reference to the Gospels (Hist. eccl. 3.39.15-16). But Papias also says that he regards the authority of the words of Jesus as transmitted by the elders from the apostles themselves to be greater than that of any information from books (Hist. eccl. 3.39.4).[…]
The earliest direct evidence for a collection of the Gospels comes from Justin Martyr (also the first to mention the Revelation of John, see Dial. 81.15), ca. 160, who makes direct reference to Matthew, Mark, Luke, and possibly John, and says that he permits the reading of ‘memoirs of the apostles or apostolic men’ (1 Apol. 66-67) in worship, one sign that the Gospels too might now be considered Christian scripture. If Justin did in fact have John, this is also the first indication of a collection of the four Gospels.[…]
The first Christian to argue for limiting the number of Gospels to four was Irenaeus of Lyons (ca. 180). Irenaeus argues further that certain other accounts may not be read because they are heretical. His implied ‘New Testament’ (a term that he uses, but not clearly referring to texts) includes the four Gospels, Acts of the Apostles (the first evidence of its use), the thirteen epistles attributed to Paul, 1 Peter, 1 and 2 John, the Revelation of John, and also the Shepherd of Hermas, a work no longer part of the New Testament canon (see. e.g., Adv. Haer. 3.21.3-4).
By the beginning of the third century, the contours of a ‘New Testament’ as we know it begin to emerge. Clement of Alexandria and Tertullian in Carthage treat as authoritative a collection of Christian documents similar to that of Irenaeus. Both approve of Hebrews (Eusebius says that Irenaeus also used Hebrews, but that cannot be demonstrated from his surviving work) and both use the epistle of Jude. Tertullian treats as scripture both the Shepherd of Hermas and the Epistle of Baranbas, another work no longer part of the New Testament. He is, furthermore, the first to use the term ‘New Testament’ in a clear reference to a collection of texts (Prax. 15).[…] Origin (ca. 185-254), whose words are preserved by Eusebius, started that there are ‘four Gospels, which alone are unquestionable’ (Hist. eccl. 6.25.4): Matthew, Mark, Luke, and John.[…]
By the fourth century, the accepted list of books that were treated as the New Testament had not changed much, as we can see from Eusebius’s Ecclesiastical History. Eusebius lists those book that everyone recognizes as scripture (homologoumena): four Gospels, Acts of the Apostles, fourteen epistles of Paul (the thirteen ascribed to him as well as Hebrews), 1 John, 1 Peter, and Revelation.[…] The emperor Constantine asked Eusebius to produce fifty copies of the Christian Bible. Unfortunately, none of these copies have survived, but Eusebius must have made a decision as to which texts to include. Two biblical codices (singular ‘codex’) from the fourth century have survived. One of these, called Sinaiticus because it was discovered in St. Catherine’s Monastery on Mount Sinai, is the oldest complete Old (Greek only) and New Testament. Its New Testament contains all the books of the modern New Testament plus the Shepherd of Hermas and the Epistle of Barnabas.[…]
After Eusebius, canon lists, some using the term ‘canon’ are drawn up in various places by various bishops or church synods. These list the books of the New Testament for the express purpose of saying ‘these books and no others.’ One of these, the Thirty-ninth Festal Letter of Bishop Athanasius of Alexandria, presents in 367, for the first time, a list of the twenty-seven books that are included in the modern New Testament.[…]Yet through this entire period, the church never adopted a set of criteria by which to determine canonicity. Although unstated, the most significant criterion for inclusion was usage and dissemination.[…] Also important was the criterion of apostolicity, that is, whether the document emanated from an apostle or was connected to an apostolic authority (e.g. Luke and Acts was associated with Paul, Mark with Peter). On the other hand, many of the now noncanonical documents were written in the names of apostles and yet were not cited as scripture by any church father: usage (or lack of it) thus took priority over ascription to an apostle. A third criterion was conformity to the proper understanding of Christianity (the regula fidea or ‘rule of faith’) as the majority church (and certainly the majority of those in power in the church) saw it.[…] ’Divine inspiration’ was not a criterion for acknowledging a document as scripture.” (The Jewish Annotated New Testament, pp 557-559)