Gary DeMar is an apologist for the preterist camp of interpreting end of the age material, as in Matt 24; the book of Revelation and the book of Daniel. Preterists claim that these prophecies were all fulfilled by the time of the destruction of the temple and Jerusalem in 70 AD.
But listen: How can this have already happened?

Matthew 24:22, 30-31, 33-34, 36 Unless those days had been cut short, no life would have been saved; but for the sake of the elect those days will be cut short. And then the sign of the Son of Man will appear in the sky, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of the sky with power and great glory. And He will send forth His angels with a great trumpet and they will gather together His elect from the four winds, from one end of the sky to the other. so, you too, when you see all these things, recognize that He is near, right at the door. Truly I say to you, this generation will not pass away until all these things take place. “But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone.
The argument here by Preterists is over “this generation”. Jesus normally used “this” to mean the current generation or the generation of that day; however here He says no man not even He knows the day or hour, so what does this say for the exact generation. literally speaking “this generation” must also have been unknown just as the day and hour was and still is an unknown, and it therefore must be the generation that actually sees the signs spoken of here leading to His coming. Those are the signs He has listed just before making this proclamation. The statement makes no sense otherwise. If He does not know the day of His coming, then He could not at that time know the generation either.
In his teaching on the “end of the world” KJV, DeMar says is translated “end of the age” in more modern translations. He then explains that the age that is taught to end is basically throughout the New Testament the age of the old covenant.  His argument is answered in chapter two in my book, And Then The End Shall Come. That chapter deals primarily with Jesus’ and Paul’s teachings on the ages.

If we accept DeMar’s preterits explanation that the Old Testament age ended with the destruction of Jerusalem and the Jewish temple in 70 AD, then Daniel and his people of the Old Testament — the saints had to be resurrected at that time based on what Daniel was told:
Daniel 12:9-13 He said, “Go your way, Daniel, for these words are concealed and sealed up until the end time. Many will be purged, purified and refined, but the wicked will act wickedly; and none of the wicked will understand, but those who have insight will understand. From the time that the regular sacrifice is abolished and the abomination of desolation is set up, there will be 1,290 days. How blessed is he who keeps waiting and attains to the 1,335 days! But as for you, go your way to the end; then you will enter into rest and rise again for your allotted portion at the end of the age.”
If 70 ad is the end of the Old Testament age and the 1290 days recorded here which is also recorded in Rev. is the end of this same age; then Daniel is risen at the very time of Jerusalem’s destruction in 70 AD. for his aloted portion. So just where is Daniel in this new covenant age. Also what do we do with Daniel 12:4 But as for you, Daniel, conceal these words and seal up the book until the end of time; many will go back and forth, and knowledge will increase.” We must ask — Is there any other time other than our own when these things have  and are happening? Did they happen in 70 AD as they are happening now?  No time has seen the advance of travel and learning to the extent that we have seen and are seeing it.
But there is only one verse from scripture needed to dispel the Preterist’s argument stating that Jesus and Paul were both speaking of the Old Covenant age when they spoke of “this age”. Luke 20:34-36 Yeshua said to them, “In this age, men and women marry; but those judged worthy of the age to come, and of resurrection from the dead, do not get married, because they can no longer die. Being children of the Resurrection, they are like angels; indeed, they are children of God.
If Jesus meant “this age” to coincide with the old covenant age and only the old covenant age, then there should be no marriage, and immortals are to be present in this the next age.
We Gentiles in this New Covenant era are said by Paul to be one with Israel not a replacement of them, and we certainly are not set apart as another age as some (most) Dispensationalists teach. Paul tells us what this means for us.

Ephesians 2:12 remember that you were at that time separate from Christ, excluded from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world.

Based on this we who are in Christ are one with Israel in the covenants. DeMar and the preterists want to make us one with them in the promise of the new covenant only, but Paul says that we were strangers to the covenants plural. So I would take this to mean that we now possess all the promised covenants given by God to Israel. This would include the land covenant. And would explain our future which is to one day rule with Christ for 1000 years.
Israel has been promised to rule the nations. We have been promised to rule with Christ for 1000 years. Jesus told the Jews that they would be the sons of God should they make it to the age to come: we are also called to be sons of God.

Yeshua said to them, “In this age, men and women marry; but those judged worthy of the age to come, and of resurrection from the dead, do not get married, because they can no longer die. Being children of the Resurrection, they are like angels; indeed, they are children of God (Luke 20:34-36 CJB). In (Luke 20:36 NASB) for they cannot even die anymore, because they are like angels, and are sons of God, being sons of the resurrection.
This day, when we will actually see the revealing of the sons of God, is the day we all look for; and it is known as the day of the Lord. The day of His reign, and of the reign of His bride with Him. We are partakers of the promises to Israel, and Israel will reign over the nations with us.
Zechariah 14:4, 6, 8-9, 11, 14, 16-18 In that day His feet will stand on the Mount of Olives, which is in front of Jerusalem on the east; and the Mount of Olives will be split in its middle from east to west by a very large valley, so that half of the mountain will move toward the north and the other half toward the south. In that day there will be no light; the luminaries will dwindle. And in that day living waters will flow out of Jerusalem, half of them toward the eastern sea and the other half toward the western sea; it will be in summer as well as in winter. And the Lord will be king over all the earth; in that day the Lord will be the only one, and His name the only one. People will live in it, and there will no longer be a curse, for Jerusalem will dwell in security. Judah also will fight at Jerusalem; and the wealth of all the surrounding nations will be gathered, gold and silver and garments in great abundance. Then it will come about that any who are left of all the nations that went against Jerusalem will go up from year to year to worship the King, the Lord of hosts, and to celebrate the Feast of Booths. And it will be that whichever of the families of the earth does not go up to Jerusalem to worship the King, the Lord of hosts, there will be no rain on them. If the family of Egypt does not go up or enter, then no rain will fall on them; it will be the plague with which the Lord smites the nations who do not go up to celebrate the Feast of Booths.
If this promise has been fulfilled please tell me when. If this promise will not be fulfilled then no promise in scripture is safe, nor can scripture be relied upon. This promise will be fulfilled and we will be the recipients of it.
On planetpreterist.com we see this statement concerning this passage and relating it to Jesus teaching on living water to the woman at the well.

“Notice how Jesus talks about living water as a symbol of the life-giving properties of God’s Spirit in this context: “Whoever drinks of this [physical] water will thirst again, but whoever drinks of the water that I shall give him will never thirst. But the water that I shall give him will become in him a fountain of water springing up into everlasting life” (John 4:14).

DeMar continues:  “Despite what many dispensationalists say, we are not going back to Temple worship in some future millennium; indeed it would be blasphemy to do so. For that matter, how, logistically, could hundreds of millions, let alone billions, of people all go up to the Temple to celebrate the Feast of Tabernacles/Ingathering? There are not nearly enough airlines in the world to physically get everyone to Jerusalem, let alone room for them when they arrived. Such thinking is foolishness! The ultimate sacrifice has been given by Jesus (cf. Heb. 10:11-18). God wants us to worship him in Spirit and in truth, not go back to the elemental things of the old covenant. The Jerusalem that people need to come to today for living water is the New Jerusalem; they need to become part of the bride (now wife)!
There is a crucial principle of hermeneutics here: the NT needs to be factored into one’s interpretation of the OT; often the interpretation that the NT gives is a spiritual one not a literal physical one. So-called literalists often neglect this principle.”
There are of course as DeMar says here many within the Dispensationalist school who call for this return to a system of animal sacrifice for Israel during the Tribulation and some even advocate for a salvation proceeding out of this turning back to the old covenant for Israel. Should we agree with Dispensationalist on this point? — No.  On the other hand the temple itself is being spiritualized by the Preterists. To them we the body of CHRIST are the Temple of God. So does that mean that the man of lawlessness will set himself up as God in us? This must be the Preterist understanding of 2 Thessalonians 2 if they spiritualize the Temple, and it would also seem to be foolishness. So both the pre-trib “literalist” and the Preterist camps contain a bit of foolishness. The literal truth however is not foolish. The scripture teaches that those we rule over with Christ are unsaved nations which the Scripture clarifies to be as scarce as pure gold. I take that to mean that the Nations will be small as most will have perished in the outpouring of Gods wrath. But these unsaved will be required to come up to Jerusalem year after year to offer sacrifice. Notice it is not even implied that we will be engaging in these sacrifices. So there will not be hundreds of millions let alone billions of people required to perform these sacrifices.
The truths that are evident in Scripture are only made clear when seen through the eyes of scripture not the eyes of man.