Development of the New Testament canon day called that of the sun" (Sunday) alongside the "writings of the prophets." A defined set of four gospels (the "Tetramorph") was asserted by Irenaeus, "c". 180, who refers to it directly. By the early 3rd century, Origen may have been using the same twenty-seven books as in the present New Testament canon, though there were still disputes over the acceptance of the Letter to the Hebrews, James, II Peter, II John, III John, Jude and Revelation, known as the Antilegomena. Likewise, the Muratorian fragment is evidence that, perhaps as early as 200, there existed a set of Christian writings
Development of the New Testament canon as now known): In the mid-2nd century, Justin Martyr (whose writings span the period from c. 145 to 163) mentions the "memoirs of the apostles", which Christians called "gospels" and which were regarded as on par with the Old Testament. Scholars are divided on whether there is any evidence that Justin included the Gospel of John among the "memoirs of the apostles", or whether, on the contrary, he based his doctrine of the Logos on it. Justin quotes the letters of Paul, 1 Peter, and Acts in his writings. In Justin's works, distinct references are found to Romans, 1 Corinthians,