New Testament Canon
The New Testament Canon is the collection of books that make up the New Testament, which has been accepted and formally approved by the Church.
By the end of the 1st century, some letters of Paul were collected and circulated. We know this through references by Clement of Rome (c. 95), Ignatius of Antioch (died 117), and Polycarp of Smyrna (c. 115). However, these texts weren't usually called Scripture as the Septuagint was, and they weren't without critics. Certain heretics tried to deny the validity of many parts of the Canon, particularly the Pauline epistles. In the late 4th century Epiphanius of Salamis (died 402) Panarion 29 says the Nazarenes had rejected the Pauline epistles; Irenaeus' Against Heresies 26.2 says the Ebionites rejected him. Acts 21:21 records a rumor that Paul aimed to subvert the Old Testament (see Romans 3:8, 31). 2 Peter 3:16 says his letters have been abused by heretics who twist them around "as they do with the other scriptures." In the 2nd and 3rd centuries Eusebius' Ecclesiastical History 6.38 stated the Elchasai "made use of texts from every part of the Old Testament and the Gospels; it rejects the Apostle (Paul) entirely"; 4.29.5 says Tatian the Assyrian rejected Paul's Letters and Acts of the Apostles; 6.25 says Origen accepted 22 canonical books of the Hebrews plus Maccabees plus the four Gospels but Paul "did not so much as write to all the churches that he taught; and even to those to which he wrote he sent but a few lines."
The Roman Emperor Constantine the Great (272-337) had a great effect on Orthodox Christianity. With his Edict of Milan in 313, Christians had more freedom and Church leadership took aggressive public stances. As a result, Church controversies now flared into public schisms, sometimes with violence. Constantine saw the quelling of religious disorder as the divinely-appointed emperor's duty and called the 314 Council of Arles against the Donatists and the First Ecumenical Council to settle some of the doctrinal problems seen as plaguing early Christianity. A number of early Christian writings were lost or destroyed during this time.