Sometimes enemies can be friends. Such is the case regarding the contribution to this topic of the testimony by those who opposed the early church. Ladd notes the opposition of the Alogi who opposed the doctrine of Jesus as the Word. They rejected the book of Revelation as they did all literature by John the Apostle, thus attesting the early tradition of John the Apostle as author.1 The witness of early Gnosticism also attributes authorship to John the Apostle:
An important witness for the apostolic authorship of Revelation has more recently come from the Gnostic materials discovered in 1945 at Chenoboskion in Upper Egypt. One of the documents is the Apocryphon of John , which cites Revelation Rev. 1:19+ and claims to be written by John, the brother of James, these who are sons of Zebedee. Helmbold cites authorities who date the Apocryphon as early as the end of the first century and notes that in any event it cannot be given a date much later than about AD 150.2
1 The first opposition to its apostolicity came from the Alogi (ca. A.D. 170), who opposed the Logos doctrine of the Fourth Gospel and therefore rejected all Johannine literature. The Alogi therefore testify indirectly to the Johannine tradition and to the tradition that the Gospel and Revelation came from the same hand.G. E. Ladd, Revelation, Book of, in Geoffrey W. Bromiley, ed., International Standard Bible Encyclopedia (Grand Rapids, MI: William B. Eerdmans Publishing Co., 1979, 1915), 4:172.