Preterists say that a key to understanding the Olivet Discourse is the statement of Jesus, that all his prophecies will occur in "this generation." [Luke 21:32] They claim that it was fulfilled in the first century.
Dispensationalists like Hal Lindsay also claim that this saying is a significant key for understanding the prophecy. Lindsay believed the 'Rapture' would likely occur by 1988, which he based on the notion that a generation was 40 years, and 1988 would be 40 years after the founding of the Jewish state in Palestine. But that date passed without a 'Rapture.' Recently some dispensationalists have speculated that perhaps a 'generation' is not 40 years, but 70 years, in which case the period when the 'Rapture' is expected would come to an end in 2018.
I also think that Jesus' reference to "this generation" is highly significant, and indeed it is a key to understanding his entire prophecy, but one should understand the prophecy in the light of Jesus' resurrection from the grave, and the fact that he is alive, and continues to represent his generation. It is a unique generation, as it spans all the time since his birth, and continues forever. The angel said to Mary, "He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David: And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end." [Luke 1:33-34]
Platonists, who believe in Plato's doctrine of the immortality of the human soul, do not understand how the generation of Jesus can be unique; they view it as like any other. Thus, they think that the meaning of "this generation" is either the generation alive in the first century when Jesus ministered, or an end-time generation. They don't believe the words of Paul to Timothy, "... That thou keep this commandment without spot, unrebukable, until the appearing of our Lord Jesus Christ: Which in his times he shall shew, who is the blessed and only Potentate, the King of kings, and Lord of lords; Who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom be honour and power everlasting. Amen." [1 Tim. 6:14-16]
Jesus is the only one who possesses immortality, according to this scripture; and therefore, his generation continues forever. This means that many of the things Jesus describes in the Olivet Discourse and Luke's parallel account span all the time from the first century to the present.
Jesus said that when Jerusalem is compassed with armies, "then know that the desolation thereof is nigh." [Luke 21:20] The Jerusalem he meant, may be either the earthly one, or the heavenly one, or, he may have alluded to both, meaning that when the earthly Jerusalem was destroyed in 70 AD, the desolation of the heavenly city was nigh. The heavenly city has been compassed by spiritual armies, in all centuries since then. This is what Peter foretold in 2 Peter 2.
In Luke 21:21 Jesus said, "Then let them which are in Judaea flee to the mountains." He must have meant flee to the promises of God that the mountains represent. Otherwise, this saying would contradict his statement in Luke 17:33, "Whosoever shall seek to save his life shall lose it; and whosoever shall lose his life shall preserve it."
I suggest the "days of vengeance" in Luke 21:22, when "all things which are written are fulfilled," are not limited to seven years at the end of the age, as dispensationalists say; neither are they the days preceding the destruction of the earthly Jerusalem as preterists claim, but they span all the time since the first century. Christ has been reigning over all, bringing his word to pass.
In verse 23, "them that are with child," and "them that give suck" should be understood in the light of the terminology of the gospel; Peter refers to the word of God as "milk." He said, "As newborn babes, desire the sincere milk of the word, that ye may grow thereby." [1 Peter 2:2] Them that "give suck" are those teaching and preaching the word. And Paul spoke of himself as a spiritual mother who "travails in birth" over the Galatian Cristians: "My little children, of whom I travail in birth again until Christ be formed in you, I desire to be present with you now, and to change my voice; for I stand in doubt of you." [Gal. 4:19-20]
So, "them that are with child" in the Olivet Discourse does not necessarily refer to girls or women who are pregnant, but to those who are ministers, who have spiritual responsibility for others.
In Luke 21:24, "Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled," refers to the Christian church, the Jerusalem above, not the earthly city. After the age of the apostles it became dominated by Gentiles, men who lacked the spirit and wisdom of God. And this continues today. The prophecy is parallel to Revelation 11:1-2, "And there was given me a reed like unto a rod: and the angel stood, saying, Rise, and measure the temple of God, and the altar, and them that worship therein. But the court which is without the temple leave out, and measure it not; for it is given unto the Gentiles: and the holy city shall they tread under foot forty and two months."
The outer court represents the worldly, outward, superficial kind of Christianity. This is also depicted in a prophecy of Daniel:
And they that understand among the people shall instruct many: yet they shall fall by the sword, and by flame, by captivity, and by spoil, many days. Now when they shall fall, they shall be holpen with a little help: but many shall cleave to them with flatteries. And some of them of understanding shall fall, to try them, and to purge, and to make them white, even to the time of the end: because it is yet for a time appointed.
And there shall be signs in the sun, and in the moon, and in the stars; and upon the earth distress of nations, with perplexity; the sea and the waves roaring;
This part of the prophecy clearly shows it is not specifically referring to events in the first century. The sun represents the gospel; the woman in Revelation 12:1 is clothed with the sun. She has the moon at her feet. This woman represents the church, those of whom Paul said: "But God, who is rich in mercy, for his great love wherewith he loved us, Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;) And hath raised us up together, and made us sit together in heavenly places in Christ Jesus." [Eph. 2:4-6]
Other scriptures show the sun becoming black like sackcloth. It means the truth of the gospel has been obscured; its message has been changed from light to superstition. The idea of unending infernal torment of unbelievers is an example of this. It fulfills Peter's prophecy in 2 Peter 2:1-3, and the whole chapter about false teachers who would come into the church.
"The sea and the waves roaring" is hardly limited to the first century, or to a future seven years; rather it refers to spiritual confusion among the people of the world. The sea refers to the people of the nations, in Revelation.
And he saith unto me, The waters which thou sawest, where the whore sitteth, are peoples, and multitudes, and nations, and tongues.
Isaiah also refers to men in unbelief as a "troubled sea."
But the wicked are like the troubled sea, when it cannot rest, whose waters cast up mire and dirt.
Perhaps Jesus was referring to the spiritual confusion and chaos among the nations of the world, when he spoke of "the sea and the waves roaring."
Also, note that Paul speaks of "winds of doctrine" in Eph. 4:14. Jesus spoke of winds and rain in Matt. 7:24-27.
Men's hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken.
Again, this seems to allude to spiritual turmoil, both in the church and in the world; the "powers of heaven" may be the spiritual powers and principalities, with whom the saints wrestle. [Eph. 6:12]
And then shall they see the Son of man coming in a cloud with power and great glory.
Christ "coming in a cloud" alludes to Daniel 7:13-14, "I saw in the night visions, and, behold, one like the Son of man came with the clouds of heaven, and came to the Ancient of days, and they brought him near before him. And there was given him dominion, and glory, and a kingdom, that all people, nations, and languages, should serve him: his dominion is an everlasting dominion, which shall not pass away, and his kingdom that which shall not be destroyed."
The saints are referred to as a "cloud of witnesses." [Heb. 12:1-3] Those who teach the word are called a "cloud" because the word is represented by "rain."
For as the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and maketh it bring forth and bud, that it may give seed to the sower, and bread to the eater: So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it. For ye shall go out with joy, and be led forth with peace: the mountains and the hills shall break forth before you into singing, and all the trees of the field shall clap their hands.
Christ is seen in the clouds of his witnesses like rainbows are sometimes seen in clouds that bring the rain.