Development of the New Testament canon a novelty in Irenaeus's time. "Against Heresies" 3.11.7 acknowledges that many heterodox Christians use only one gospel while 3.11.9 acknowledges that some use more than four. The success of Tatian's Diatessaron in about the same time period is "...a powerful indication that the fourfold Gospel contemporaneously sponsored by Irenaeus was not broadly, let alone universally, recognized." Irenaeus apparently quotes from 21 of the New Testament books and names the author he thought wrote the text. He mentions the four gospels, Acts, the Pauline epistles with the exception of Hebrews and Philemon, as well as the first epistle of Peter, and
Historical reliability of the Gospels exception, although the author simply refers to himself as "the disciple Jesus loved" and claims to be a member of Jesus' inner circle. During the following centuries, each canonical gospel was attributed to an apostle or to the close associate of an apostle. Most scholars have rejected the traditional attributions. The gospels of Matthew, Mark, and Luke are referred to as the Synoptic Gospels because of a similar sequence and wording. They are also composed in Koine Greek and the majority of Mark and roughly half of Matthew and Luke coincide in content, in much the same sequence, often nearly