Readers currently assume that John the Apostle could not be the author of the last book of the Bible, the Revelation. Here are the reasons that it seems quite clear that John the Apostle is the author:
The text of the Revelation seems to identify which servant John is its author by saying it is the John “who bore witness to the word of God, and to the testimony of Jesus Christ, even to all that he saw.” This could be read as referring to all that he saw on Patmos. Yet it may mean that this John is an eyewitness of the teachings and passion of Jesus. There seems to be no reason that this could not refer to the things told in the Gospel of John, and to all that he saw while he went about with Jesus through his life, death, and resurrection. As the one Apostle present at the Crucifixion, he is the fullest witness. The same statement, “the word of God and the testimony of Jesus,” occurs at 1:9, referring to the reason John was sent to Patmos to begin with—that is, prior to the vision. And again the phrase occurs referring to the reason that the martyrs are beheaded (20:4), as was his brother James. The Apostles are the eye witnesses of the Gospel. John is the last of the Apostles, the only one alive in the last decade of the first century, and the only John sent to Patmos. So the end of the Gospel of John (“this is the disciple who is bearing witness to these things…”) seems to lead into the beginning of the Revelation (“…John, who bore witness to the word of God and to the testimony of Jesus Christ, even to all that he saw”).
One reason that the Gospel of John and the Revelation seem to have been written by the same author is that while the other three gospels have an apocalyptic section, recalling the teaching of Jesus on the coming of the Kingdom, the Gospel of John does not, so that the two fit together quite nicely. For unlike Matthew in Chapter 24, Mark in Chapter 13, and Luke in Chapter 21, the Gospel of John does not contain a late section of the words of Jesus regarding the end times. It is just as if the author left these things to be discussed elsewhere, or was content with that discussion. His apocalypse will be that of the risen Christ.
The Apocalypse section in the Gospel of John is very brief, occurs early, and describes the resurrection of the dead (5:28-29), as in the twentieth chapter of the Revelation. It begins:
“The one who hears my word and believes him who sent me has eternal life; he does not come into judgment, but has passed from death into life…Truly, truly, I say to you, the hour is coming, and now is, when the dead will hear the voice of the son of God, and those who hear will live…Do not marvel at this; for the hour is coming when all who are in the tombs will hear his voice and come forth, those who have done good to the resurrection of life, and those who have done evil, to the resurrection of judgment.”
Together with the passage in Luke, “the kingdom is not coming with signs to be observed,” the kingdom is present. And so these passages are the basis of the reading that these things are entirely spiritual, and not coming at all, in the sense in which we read it “with signs to be observed.” “…But if it is by the Spirit of God that I cast out demons, then the Kingdom of God has come upon you” (Matthew 12:28). The things of the Revelation, like the incarnation, describe how being is, always, and what is always true: The Kingdom of heaven is accessible now, and in the most fundamental sense, is present, though we do not come into it. The hour is now when the dead will hear his voice and rise. This is the sense in which the coming of the Kingdom begins with the incarnation, like a mustard seed. It may be, because being is this way, that human history and the world in time unfold in this way; and this would be the most fundamental source of prophecy: It is because things are the way they are that their unfolding in time can be foreseen. The resurrection is both present and future, though in John it is emphatically also future: “And I will raise him up at the last day” (John 6:40; 44; 12:48). The future kingdom is assumed but not addressed in the Gospel of John. Though the statement is an attempt to write what Jesus said and not what John said, still, it is very interesting to wonder whether the Apocalypse could have been seen and written yet when John wrote his gospel. The above passage reminds of those in Chapter 20 of the Revelation, those over whom the second death has no power (20:6). The Revelation, then, seems to fit together with the Gospel of John as the missing Apocalypse obviously authored by the Apostle.
Contemporary readers think it to be conclusive that the Revelation could not have been written by John the Apostle (David Aune, 1997, pp. xlviii-lx). And so this question has seemed to us a good place to begin. The tradition seems otherwise to always have assumed that John the Apostle is the author, beginning, in preserved writings, in about 155-160 A.D., with Justin (Dialogue with Trypho, 81; p. 40 below). It is not clear whether Justin cites the book or an oral report of the teaching of John, or how widely circulated the book was. It may have been a secret work in the first half of the second century, or the preserve of the churches in Asia. Dionysius the Great, Bishop of Alexandria, writing in the fourth century, seems to be the first of preserved writers to doubt that the apostle John wrote the Revelation. Dionysius suggests that the apocalypse was seen by a different John (Roberts, A., and Donaldson, J. The Ante-Nicene Fathers (Vol. VII, pp. 82-84). One reason for his doubt is that in the gospel and first letter, John the Apostle does not refer to himself by name. And so it is thought, since the John of the Revelation does call himself John, that this is likely to be another John. Yet surely John might identify himself in one writing and not do so in another, and this is less an argument than a hunch. Dionysius also comments that in the Revelation, none of John’s characteristic “phrasing or diction” appears to be present. The writings “share hardly a syllable in common,” and unlike the gospel and letters, the Revelation employs “barbarous idioms” and a dialect and language that are “not of the exact Greek type.” We will consider in place below certain symbols, such as the door, the way of speaking about being, and about the divinity of Jesus, that seem nearer to John than anyone else known in history. A characteristic phrase is “to prepare a place,” in the Gospel of John 14:2-3 and Revelation 12:6; Aune, 1997, p. 691). Modern linguistics notes that the rate of the use of words unique to the text is similar to the Gospel of John, and the use of the preposition ek is similarly higher in the Gospel of John and the Revelation than in any other Greek Biblical text (Aune, ccvii; cixxix). The identification of Jesus with the Word, though, is the most obvious similarity (Revelation 19:13; John 1:1), and it may even be safe to say that no one else in the history of humanity is able to speak and write in this way. The “Lamb of God” is another characteristic name from John the Baptist, as reported in the Gospel of John (1:29). Aquinas notices the light in the gospel (John 1:9), letter (1 John 1:5) and Revelation (22:5, Summa Contra Gentiles, III. 53). There is, though, quite a difference between the Gospel of John and the prophetic vision of the Revelation. One wonders how much of the difference might be due to the dictated and descriptive character of the Revelation, or to John having been told what to write. He is simply shown what he saw, and told to write this. We need not presuppose that it is impossible for these things to have occurred just as they are written. So in the dictated letters to the churches, there are different concerns, for example regarding heresy and idolatry, than in the three letters of John. If one compares, for example, the writing preserved of Polycarp and Papias, or even Justin or Irenaeus, it is difficult to believe that anyone capable of the height of thought in receiving the Revelation was alive in the first or Second Century other than the author of the Gospel of John. Jung believes John to be the author of the gospel, the Revelation and the letters as well, writing that “psychological findings speak in favor of such an assumption” “Answer to Job,” in The Portable Jung, p. 625, 636 note 177.
Wilbur Smith (Holy Bible, 1881, p. 28) gives a fine summary of the reasons it is obvious that John wrote the Revelation:
…The evidence in favor of St. John’s authorship consists of the assertions of the author and historical tradition… The author’s description of himself in the first and [last] chapters is certainly equivalent to an assertion that he is himself the apostle. He names himself simply John…He is also described as a servant of Christ, one that had borne testimony as an eyewitness of the word of God and of the testimony of Christ–terms which were surely designed to identify him with the writer of the verses John 19:35; 1:14, and 1 John 1:2. He is in Patmos for the word of God and the testimony of Jesus Christ. It may be easy to suppose that other Christians of the same name were banished thither, but the Apostle is the only John who is directly named in early history as an exile at Patmos. He is also a fellow sufferer with those whom he addresses, and the authorized channel of the most direct and important communication that was ever made to the seven churches of Asia, of which churches John the Apostle was at that time the spiritual governor and teacher. Lastly, the writer was a fellow servant of angels and a brother of prophets, titles which are far more suitable to one of the chief Apostles, and far more likely to have been assigned to him than to any other man of less distinction. All these remarks are found united together in the Apostle John, and in him alone of all historical persons.
The theory that John was not the author may require that the text is lying or misrepresenting itself. While this is possible, and not unheard of, there is no reason to think that is what is occurring here. Similarly, in the face of the admonition not to alter the text (22:19), it seems unlikely that followers of John did much editing, let alone writing on it, though it would not be surprising if John himself did some work on it.
The decisive consideration, though, is in the text and not the notes: John does not include an apocalyptic section in his Gospel, as the other 3 do. The reason is that it occupies a separate work. The Apostle John is the very eye witness, from beginning to end, referred to in the text of the Revelation.