During the fourth and fifth centuries the tendency to exclude the Apocalypse
from the list of sacred books continued to increase in the Syro-Palestinian churches. Eusebius expresses no definite opinion. He contents himself with the statement: "The Apocalypse is by some accepted among the canonical books but by others rejected" (Church History III.25). St. Cyril of Jerusalem does not name it among the canonical books (Catechesis IV.33-36); nor does it occur on the list of the Synod of Laodicea, or on that of Gregory of Nazianzus. Perhaps the most telling argument against the apostolic authorship of the book is its omission from the Peshito, the Syrian Vulgate
http://www.newadvent.org/cathen/01594b.htm
: in
very early Christianity to prove these are two different writers. Eighteen hundred years ago, Dionysius (Bishop of the Patriarchy of Alexandria) stated that "Revelation" was not written by the same person who wrote John's Gospel and Letters. (Eusebius' History of the Church, 7.25) His opinion came from his comparing their two writing styles and found John Patmos to be entirely different from John Apostle and any other New Testament writer
English Standard Version (ESV)
16 “I, Jesus, have sent my angel to testify to you about these things for the churches. I am the root and the descendant of David, the bright morning star