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 studying the reliability of the gospels, as Acts was seemingly written by the same author as the "Gospel of Luke". Historians subject the gospels to critical analysis, attempting to differentiate, rather than authenticate, reliable information from possible inventions, exaggerations, and alterations. Since there are more than 15,000 New Testament manuscripts which present hundreds of thousands of textual variants, scholars use textual criticism to determine which gospel variants could theoretically be taken as 'original'. To answer this question, scholars have to ask who wrote the gospels, when they wrote them, what was their objective in writing them, what sources the authors