Athanasius and Canon of New Testament
Athanasius (c. 300 to 373 AD) was bishop of Alexandria from 328 to 373 AD. He was known as one of strong opponent of Arianism. His festal letters were his homilies where in one of them he gave list of Old and New Testament books. His list of New Testament books is the earliest known list with twenty-seven books as we have now (English translation from The Nicene and Post-Nicene Fathers, Series II, Vol. 14, Vol. 4):
Again it is not tedious to speak of the [books] of the New Testament. These are, the four Gospels, according to Matthew, Mark, Luke, and John. Afterwards, the Acts of the Apostles and Epistles (called Catholic), seven, viz. of James, one; of Peter, two; of John, three; after these, one of Jude. In addition, there are fourteen Epistles of Paul, written in this order. The first, to the Romans; then two to the Corinthians; after these, to the Galatians; next, to the Ephesians; then to the Philippians; then to the Colossians; after these, two to the Thessalonians, and that to the Hebrews; and again, two to Timothy; one to Titus; and lastly, that to Philemon. And besides, the Revelation of John.
But for greater exactness I add this also, writing of necessity; that there are other books besides these not indeed included in the Canon, but appointed by the Fathers to be read by those who newly join us, and who wish for instruction in the word of godliness. ……..and that which is called the Teaching of the Apostles, and the Shepherd. But the former, my brethren, are included in the Canon, the latter being [merely] read; nor is there in any place a mention of apocryphal writings.
Athanasius, 39th Festal Letter
Athanasius distinguished three categories of books: accepted (27 books), edifying (Didache or Teaching of the Apostles and Shepherd of Hermas) and apocrypha (not to be read at all). Though having the same books as our present New Testament, books in his list have different order: four Gospels, Acts, seven Catholic epistles (James, 1 Peter, 2 Peter, 1 John, 2 John, 3 John and Jude), fourteen Paul’s epistles (he attributed Hebrews to Paul and had it before Paul’s pastoral epsitles) and ends with Revelation.