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
Development of the Old Testament canon of the Catholic Church. All of these we also judge to be Canonical Books, and confess them to be Sacred Scripture. Not all books of the Old Testament are covered in the "Prophetologion", the official Old Testament lectionary: "Because the only exposure most Eastern Christians had to the Old Testament was from the readings during services, the Prophetologion can be called the Old Testament of the Byzantine Church." Development of the Old Testament canon The Old Testament is the first section of the two-part Christian Biblical canon; the second section is the New Testament. The Old Testament includes the books