A skeletal explanation and defense of “two-stage” preterism:
The New Testament envisions three basic eschatological events: the conclusion of the Old Covenant with the destruction of Jerusalem and the Temple in AD 70, the conquest of the pagan Roman Empire by the Messiah, and a day of final judgment and new creation. Two of these events have already happened, thus two-stage preterism. Jesus, as the last prophet to Israel, was primarily concerned with the first of these. Paul, as the apostle to the Gentiles, was primarily concerned with the second (something which many forms of preterism miss). The book of Revelation, as the great charter prophetic text of the New Covenant era, is concerned with all three in chronological order.
Jesus’ prophetic ministry was largely about AD 70. The Old Covenant era was ending. Under the Old Covenant, Israel had incurred the full measure of God’s wrath. They had a final chance to rally around the Messiah, repent, and enter the New Covenant, but they largely failed to do so. Jesus prophesied that if they did not repent, they would be destroyed by Rome and (partially literally) cast into Gehenna, the burning valley of refuse outside Jersualem. But Jesus began rebuilding Israel around Himself with the Apostles, and they would be the core of a reborn Israel who would escape the wrath to come and carry on the existence of the people of God into New Covenant. The Olivet Discourse is simply about this prediction. The Son of Man would symbolically come on the clouds (as Yahweh came with the clouds to judge in the Psalms and prophets) and be vindicated as God’s Messiah and the leader of the true Israel.
Jesus’ Messianic victory, however, was not simply for Israel but was intended to bless the world and bring the nations under the reign of God. The Gentile world, embodied in the Roman Empire, reveled in idolatry and oppressed Israel and the Church. God would use their armies as He used the Babylonians and the Assyrians in the past to punish His faithless people, and after that He would punish them for their own sins. Jesus’ people, following His lead, began a campaign of conquest through the witness of preaching and martyrdom. They shed their own blood to defeat the Beast, and defeat him they did. By the time of Constantine and Theodosius, they had largely won the war. The pagan empire converted, and the nations came to confess Jesus as Lord to the glory of God the Father. Shortly thereafter, the Roman Empire was more or less deceased, but Christ was still honored as King throughout the known world.
Even under Jesus’ rule, however, the nations would be subject to death and the curse. This is partially undone in the present life of the Church but awaits a final conclusion. Creation needs to be freed from its bondage and futility. Humans need glorifed bodies. Inexhaustible life and glory still need to fill all that God has made, and heaven and earth still need to become one place, where we can again touch and see God in Jesus. This will happen at the end of history after an unprecedented final rebellion.
Biblical support for all of this is found primarily by reading Jesus, Paul, and Revelation in light of the Old Testament prophets. In the prophets, catastrophic cosmic language and many vivid and stange symbols were used to describe massive socio-political events like invading Gentile armies or return from Exile. The sun, moon, and stars being affected represents changes in authorities and governments. The earth being affected represents changes in the common people. One like a son of man ascends up the cloud to the Ancient of Days to receive a kingdom over all kingdoms, and this represents Christ and His people being vindicated and receiving the kingdoms of the earth. The language of New Testament prophecy links tightly with the language of Old Testament prophecy and helps us to see how it is largely of the same nature: apocalyptic descriptions of massive events in history.
The book of Revelation in particular follows the general pattern of many Old Testament prophetic books. It first addresses the people of God in the present, moves on to discuss the judgment God will be sending on His own unrepentant people through pagan armies, turns to prophesy the eventual judgment of the pagan powers themselves for their many crimes, and finally promises an ultimate restoration and happy ending for those who persevere in faith through it all. That the seven seals match closely the disaster lists from the Olivet Discourse shows that the destruction of Jerusalem is the first prophesied event, the clear identity of the Beast with the Roman Empire shows that its conquest by the witness of the martyrs is the second prophesied event, and the millennial gap and abolition of Death and Satan show that a final consummation lies at the end of it all.
At this point, I won’t attempt any more detailed defense of this two-stage preterism, but I think it makes very, very good sense of the biblical data. It accounts easily for everything Jesus, Paul, and John say about eschatology. It respects the Old Testament background and takes its symbolism seriously as interpretive keys to New Testament apocalyptic. Perhaps most importantly, as with all orthodox forms of preterism, it allows Jesus’ and John’s words about events which would take place soon to have undiluted force while also giving a strong place for final judgment and the eschatological Resurrection.