In his Ecclesiastical History, Eusebius (AD 264-340) set out the results of research he had conducted into which books were accepted as inspired by different churches around the Roman Empire. He found four classes of books: The first were those which were universally accepted which were most of the NT: Four Gospels, Acts, fourteen letters of Paul, 1 Peter, 1 John and Revelation. The second category were those books accepted by the majority of churches, including himself: James, 2 Peter, 2 & 3 John and Jude. His third category were what he called spurious books or rejected writings (The Acts of Paul, Shepherd of Hermas, Apocalypse of Peter, Epistle of Barnabas, The Didache). His final group were heretical writings (Gospel of Peter, Gospel of Thomas, Acts of Andrew, Gospel of Matthias, Acts of John).
Ecclesiastical History 3:25
1. Since we are dealing with this subject it is proper to sum up the writings of the New Testament which have been already mentioned. First then must be put the holy quaternion of the Gospels; following them the Acts of the Apostles.
2. After this must be reckoned the epistles of Paul; next in order the extant former epistle of
John, and likewise the epistle of Peter, must be maintained. After them is to be placed, if it really seem proper, the Apocalypse of John, concerning which we shall give the different opinions at the proper time. These then belong among the accepted writings.
3. Among the disputed writings, which are nevertheless recognized by many, are extant the so-called epistle of James and that of Jude, also the second epistle of Peter, and those that are called the second and third of John, whether they belong to the evangelist or to another person of the same name.
4. Among the rejected writings must be reckoned also the Acts of Paul, and the so-called Shepherd, and the Apocalypse of Peter, and in addition to these the extant epistle of Barnabas, and the so-called Teachings of the Apostles; and besides, as I said, the Apocalypse of John, if it seem proper, which some, as I said, reject, but which others class with the accepted books.
5. And among these some have placed also the Gospel according to the Hebrews, with which those of the Hebrews that have accepted Christ are especially delighted. And all these may be reckoned among the disputed books.
6. But we have nevertheless felt compelled to give a catalogue of these also, distinguishing those works which according to ecclesiastical tradition are true and genuine and commonly accepted, from those others which, although not canonical but disputed, are yet at the same time known to most ecclesiastical writers — we have felt compelled to give this catalogue in order that we might be able to know both these works and those that are cited by the heretics under the name of the apostles, including, for instance, such books as the Gospels of Peter, of Thomas, of Matthias, or of any others besides them, and the Acts of Andrew and John and the other apostles, which no one belonging to the succession of ecclesiastical writers has deemed worthy of mention in his writings.
7. And further, the character of the style is at variance with apostolic usage, and both the thoughts and the purpose of the things that are related in them are so completely out of accord with true orthodoxy that they clearly show themselves to be the fictions of heretics. Wherefore they are not to be placed even among the rejected writings, but are all of them to be cast aside as absurd and impious.