The question of how we know the 66 books in most Bibles are truly authorized as part of the canon, the authoritative collection of inspired Scripture, is fundamental. The canon was not unilaterally decided by the early Catholic Church; rather, the Church accepted a canon that was already set, as evidenced by the agreement among 25,000 ancient copies of the New Testament in various languages. Only a few books—James, Jude, II Peter, and II and III John—raised questions of canonicity due to authorship disputes, yet all are attested in early writings as authoritative. By AD 140, the visible church recognized all fourteen of Paul's letters and the four gospels, with the first historical list of all 27 New Testament books dating to AD 367, and official ratification by papal decree in AD 405. The Bible contains internal authorization protocols, including the prophecy in Isaiah 8:16, understood by the early church to mean the canon would be completed by the death of the original twelve apostles. The apostle John, the last to die around AD 100, is supposed to have gathered the 27 New Testament books and authorized their use in churches. Evidence suggests Peter began this canonization process as early as the mid-AD 60s, as II Peter 3:15-16 indicates Paul's epistles were already considered Scripture. This process potentially included nineteen books initially, with John later adding his writings, bringing the total to 24, leaving only Matthew's Gospel, James, and Jude, all written by apostles and without legitimate canonical issues. Protocols for canonicity include apostolic authorship, with exceptions for Luke and Mark, whose works were under the supervision of Paul and Peter, respectively. Another key protocol is internal unity, evident in the agreement of the New Testament books on doctrine, Christian living, history, and prophecy, forming a cohesive whole in 27 parts. Other suggested texts, like the Gospel of Thomas, disturb this unity and were excluded. General acceptance by the church also played a role, with the 27 books eventually authorized before the rise of the organized Catholic Church in the second century AD. The 39 books of the Old Testament underwent similar tests of canonicity, with a few like Esther and parts of Daniel questioned but ultimately recognized as reliable. Texts such as the Apocrypha and the Book of Enoch were deemed of lesser quality compared to the accepted books. The biblical books among the Dead Sea Scrolls further attest to the precision of their transmission through the ages, and scholarly debate on Old Testament canonicity has largely subsided to minor disputes.