In the second half, then, of the second century there was a canon of the New Testament consisting of two parts called _the gospel_(187) and _the apostle_.(188) The first was complete, containing the four gospels alone; the second, which was incomplete, contained the Acts of the Apostles and epistles, _i.e._, thirteen letters of Paul, one of Peter, one of John, and the Revelation. How and where this canon originated is uncertain. Its birthplace may have been Asia Minor, like Marcion's; but it may have grown about the same time in Asia Minor, Alexandria, and Western Africa. At all events, Irenæus, Clement of Alexandria, and Tertullian agree in recognizing its existence.
Irenæus had a canon which he adopted as apostolic. In his view it was of binding force and authoritative. This contained the four gospels, the Acts, thirteen epistles of Paul, the first epistle of John, and the Revelation. He had also a sort of appendix or deutero-canon, which he highly esteemed without putting it on a par with the received collection, consisting of John's second epistle, the first of Peter, and the Shepherd of Hermas. The last he calls _Scripture_.(189) The epistle to the Hebrews, that of Jude, James's, second Peter, and third John he ignored.
Clement's collection was more extended than Irenæus'. His appendix or deutero-canon included the epistle to the Hebrews, 2 John, Jude, the Apocalypse of Peter, the Shepherd of Hermas, the Epistles of Clement and Barnabas. He recognized no obligatory canon, distinct and of paramount authority. But he separated the New Testament writings by their traditionally apostolic character and the degree of importance attached to them. He did not attach the modern idea of _canonical_ in opposition to _non-canonical_, either to the four gospels or any other part of the New Testament. Barnabas is cited as an apostle.(190) So is the Roman Clement.(191) The Shepherd of Hermas is spoken of as _divine_.(192) Thus the line of the Homologoumena is not marked off even to the same extent as in Irenæus.
Tertullian's canon consisted of the gospels, Acts, thirteen epistles of Paul, the Apocalypse, and 1 John. As an appendix he had the epistle to the Hebrews, that of Jude, the Shepherd of Hermas, 2 John probably, and 1 Peter. This deutero-canon was not regarded as authoritative. No trace occurs in his works of James' epistle, 2 Peter, and 3 John. He used the Shepherd, calling it _Scripture_,(193) without implying, however, that he put it on a par with the usually acknowledged canonical writings; but after he became a Montanist, he repudiated it as the apocryphal Shepherd of adulterers, "put among the apocryphal and false, by every council of the churches."(194) It was _not_, however, reckoned among the spurious and false writings, either at Rome or Carthage, in the time of Tertullian. It was merely placed outside the universally received works by the western churches of that day.