There are four general approaches to Revelation as a book of prophecy. The most popular by far is the futurist approach. This approach primarily reads Revelation as a book about things that haven’t even happened yet today. Certainly there are elements of Revelation that have not happened yet. For example, Jesus has not yet returned to earth in any literal way. The final resurrection and judgment have not taken place. Many Christians feel that, if they could just understand the imagery of Revelation, they would have a blueprint for the final events of history.
At the same time, John says he is writing about things that are “soon” (1:1). Another approach to Revelation is the preterist approach that sees most of the imagery of Revelation as symbolism about John’s own time. As I just argued above, prophecy wasn’t usually about the far distant future, at least not in the first place. So wouldn’t our first expectation be that Revelation was primarily about the near future of the churches in Asia Minor, to which this scroll was first written?
A middle way between the two previous approaches is the historicist approach. This approach sees Revelation predicting events throughout the last two thousand years of church history. For example, if Babylon symbolizes the Roman Empire, then it did not fall until several hundred years after John was writing. In the past, some have also wanted to make the seven churches of Revelation 2-3 into an allegory of the ages of church history.
Finally, the idealist approach worries less about the concrete references John may have originally pictured and looks more to the timeless struggle between Christ and Satan that goes on in every age. In this approach, we should not so much look to what this symbol predicts or what that image specifically represents but see Revelation more in terms of types of struggles and types of opponents that Christians will face repeatedly in this world.
In my own reading, I have found elements of all of these in Revelation. Certainly I believe that we should start with the assumption that the book of Revelation was relevant to its first audience. Yet its contemporary images quickly blur off into the types of struggles and opponents Christians have faced repeatedly throughout time. And we are also still looking to the final return of Christ in salvation, accompanied by a final resurrection and judgment.