Athanasius, a 4th-century bishop of Alexandria and a significant theologian, delimited the canon and settled the strife between East and West. On a principle of inclusiveness, both Revelation and Hebrews (as part of the Pauline corpus) were accepted. The 27 books of the New Testament—and they only—were declared canonical. In the Greek churches there was still controversy about Revelation, but in the Latin Church, under the influence of Jerome, Athanasius’ decision was accepted. It is notable, however, that, in a mid-4th-century manuscript called Codex Sinaiticus, the Letter of Barnabas and the Shepherd of Hermas are included at the end but with no indication of secondary status, and that, in the 5th-century Codex Alexandrinus, there is no demarcation between Revelation and I and II Clement.

In the Syriac Church, Tatian’s Diatessaron was used until the 5th century, and in the 3rd century the 14 Pauline Letters were added. Because Tatian had been declared a heretic, there was a clear episcopal order to have the four separated Gospels when, according to tradition, Rabbula, bishop of Edessa, introduced the Syriac version known as the Peshitta—also adding Acts, James, I Peter, and I John—making a 22-book canon. Only much later, perhaps in the 7th century, did the Syriac canon come into agreement with the Greek 27 books.

Developments in the 16th century

With the advent of printing and differences between Roman Catholics and Protestants, the canon and its relationship to tradition finally became fixed. During the Counter-Reformation Council of Trent (1545–63), the canon of the entire Bible was set in 1546 as the Vulgate, based on Jerome’s Latin version. For Luther, the criterion of what was canonical was both apostolicity, or what is of an apostolic nature, and “was Christum treibet”—what drives toward, or leads to, Christ. This latter criterion he did not find in, for example, Hebrews, James, Jude, and Revelation; even so, he bowed to tradition, and placed these books last in the New Testament.

The physical aspects of New Testament texts

To establish the reliability of the text of ancient manuscripts in order to reach the text that the author originally wrote (or, rather, dictated) involves the physical aspects of the texts: collection, collation of differences or variant readings in manuscripts, and comparison in matters of dating, geographical origins, and the amount of editing or revision noted, using as many copies as are available. Textual criticism starts thus with the manuscripts themselves. Families of manuscripts may be recognized by noting similarities and differences, degrees of dependence, or stages of their transmission leading back to the earliest text, or autograph. The techniques used in textual studies of ancient manuscripts are the same whether they deal with secular, philosophical, or religious texts. New Testament textual criticism, however, operates under unique conditions because of an abundance of manuscripts and the rather short gap between the time of original writing and the extant manuscripts, shorter than that of the Old Testament.

Compared with other ancient manuscripts, the text of the New Testament is dependable and consistent, but on an absolute scale there are far more variant readings as compared with those of, for example, classical Greek authors. This is the result, on the one hand, of a great number of surviving manuscripts and extant manuscript fragments and, on the other, of the fact that the time gap between an oral phase of transmission and the written stage was far shorter than that of many other ancient Greek manuscripts. The missionary message—the kerygma (proclamation)—with reports of the Passion, death, Resurrection, and Ascension of Jesus Christ and collections of his deeds and sayings was, at first, oral tradition. Later it was written down in Gospel form. The letters of Paul, Apostle to the Gentiles who founded or corresponded with churches, were also collected and distributed as he had dictated them. All autographs of New Testament books have disappeared. In sharp contrast to the fact that the oldest extant full manuscript of a work by the Greek philosopher Plato (died 347 bce) is a copy written in 895—a gap of more than 1,000 years bridged by only a few papyrus texts—there was a time gap of less than 200 or 300 years between the original accounts of the New Testament events and extant manuscripts. In fact, a small (about 2.5 inches by 3.5 inches [6.4 by 8.9 centimetres]) papyrus fragment with verses from the 18th chapter of the Gospel According to John can be dated c. 120–130; this earliest known fragment of the New Testament was written 40 years or less after the presumed date of the production of that Gospel (c. 90).

Excluding papyri found preserved in the dry sands, as in Egypt (where the Gospel According to John was evidently popular judging from the large number of fragments found there), the approximate number of New Testament manuscripts dating from the 3rd to 18th centuries are: 2,000 of the four Gospels; 400 of Acts, Pauline, and Catholic letters together; 300 of Pauline letters alone; 250 of Revelation; and 2,000 lectionaries—i.e., collections of gospel (and sometimes Acts and letter) selections, or pericopes, meant to be used in public worship. Quotations from the Church Fathers—some of which are so extensive as to include almost the whole New Testament—account for more than 150,000 textual variants. Of the quotations in the Fathers, however, it is difficult to make judgments because the quotations may have been intended to be exact from some particular text traditions, but others may have been from memory, conflations, harmonizations, or allusions. Of the many New Testament manuscripts to date, however, only about 50 contain the entire 27 books of the New Testament. The majority have the four Gospels, and Revelation is the least well attested. Prior to the printing press (15th century), all copies of Bibles show textual variations.