Despite popular opinion, the Book of Revelation does not undermine the postmillennial hope. If fact, it does the opposite: it underscores. But before one can interpret Revelation properly he must understand when John wrote it. In that it is important to determine the date of Revelation in order to understand what John was writing about, I have been looking at the internal evidence in Revelation which shows that it was written prior to the Jewish temple’s destruction in AD 70. In this posting I will provide a brief sample of early-date evidence from church history and tradition. I will summarize the evidence from four early Christian writings.
1. The Shepherd of Hermas
The Shepherd of Hermas is little known among evangelical laymen today. But in the first three centuries of the Christian era it was so influential that Irenaeus, Origen, Jerome and many others deemed it canonical.  It even appears in the Codex Sinaiticus, one of the best preserved ancient copies of the whole Bible. 
Virtually all scholars agree that the Shepherd of Hermas draws upon Revelation as the source of its imagery — even late date advocates like H. B. Swete, R. H. Charles, and Robert Mounce.  This would demand that Revelation be written, copied, and circulated prior to the composition of the Shepherd.
A good deal of debate exists regarding its date of composition and, thus, this line of evidence cannot serve as a conclusive argument. Nevertheless, the strong possibility exists that it was written in the A.D. 80s. In fact, Philip Schaff decisively supports an early date for The Shepherd, even allowing that it most probably was written by the very Hermas mentioned in Romans.  J. B. Lightfoot cites several writers supportive of the earlier date: Cotelier, Cave, Lardner, Gallandi, Lumper, Lachmann, Sprinzl.  More recently still, Lawson , Goodspeed , and others concur in the view that it was written in the A.D. 90s. The two leading evidentiary avenues are: (1) It was written by a Hermas, who seems to be the one Paul refers to in Romans 16:14. (2) Many church fathers thought it canonical. This suggests its composition around the time of the apostles, or shortly after. If this date, as argued by John A. T. Robinson  and others, is correct, then Revelation, upon which it depended, would have been written earlier — long before A.D. 95 and almost certainly pre-A.D. 70.
2. Papias (A.D. 60-130)
Papias, a disciple of John, writes that James and John suffered martyrdom together at the hands of the Jews.  We know that James died before the destruction of the temple, and even late date advocate H. B. Swete admits that Papias must have felt at the very least that John died no later than the destruction of the temple.  This would make Revelation, if written by John, to be earlier still.
3. The Muratorian Canon (ca. A.D. 170)
The Muratorian Canon is the earliest surviving list of canonical books. In this very important manuscript we read: “The blessed Apostle Paul, following the rule of his predecessor John, writes to no more than seven churches by name.”  Consequently, Paul’s last writing to a church could not have preceded John’s writing of Revelation, for here we read that Paul follows John in writing to seven churches. This demands that the writer hold a view of date earlier than A.D. 67 or 68 for Revelation, in that Paul’s was beheaded in A.D. 67-68. 
4. Clement of Alexandria (A.D. 150-215)
Clement of Alexandria does not specifically mention the name of the emperor of the banishment. But he does believe Revelation is inspired revelation from God and was written by the apostle John.  And he dogmatically states in his Miscellanies 7:17: “The teaching of our Lord at His advent, beginning with Augustus and Tiberius, was completed in the middle of the times of Tiberius. And that of the apostles, embracing the ministry of Paul, ends with Nero.” Thus, he is a witness for the early date of Revelation.
1. Jerome, On the Lives of Illustrious Men 10. Irenaeus Against Heresies 4:20:2. Origen in his commentary on Romans 16:14.
2. J. B. Lightfoot and J. R. Harmer, The Apostolic Fathers (Grand Rapids: Baker, rep. ), 294.
3. R. H. Charles, The Revelation of St. John (ICC) (Edinburgh: T & T Clark, 1920), 1:xcvii; Henry Barclay Swete, Commentary on Revelation (Grand Rapids: Kregal, 1977 [rep. 1906]), cx. Robert H. Mounce, The Book of Revelation (NICNT) (Grand Rapids: Eerdmans, 1977), 37.
4. Schaff, History of the Christian Church, 2:688ff.
5. Lightfoot and Harmer, The Apostolic Fathers, 294.
6. John Lawson, A Theological and Historical Introduction to the Apostolic Fathers (New York: Macmillan, 1961), 225.
7. Edgar J. Goodspeed, The Apostolic Fathers (New York: Harper, 1950), 97 and A History of Early Christian Literature (Chicago: University of Chicago, 1942), pp. 47-48.
8. Robinson, Redating the Book of Revelation, 319-320.
9. See: Swete, Revelation, clxxix-clxxx and Lightfoot and Harmer, Apostolic Fathers, 519, 531.
10. Swete, Revelation, pp. clxxix-clxxx.
11. Alexander Roberts and Philip Schaff, The Ante-Nicene Fathers (Grand Rapids: Eerdmans, rep. n.d. ), 5:603. The seven churches addressed by Paul would be Rome, Corinth, Galatia, Ephesus, Philippi, Colassae, and Thessalonica.
12. A. T. Robertson, “Paul” in James Orr and John Nuelson, eds., International Standard Bible Encyclopedia (Grand Rapids: Eerdmans, 1929), 3:2287; Richard Longenecker, The Ministry and Message of Paul (Grand Rapids: Zondervan, 1971), 86.
13. Clement, Who is the Rich Man? 42 and Miscellanies, 6:13.