“a new heaven and a new earth.” Two times in the future there will be “a new heaven and a new earth.” The “new heaven and earth” here in Isaiah 65:17 is the heaven and earth of Christ’s Millennial Kingdom on earth. The phrase “a new heaven and a new earth” can be confusing because Revelation 21:1 also says, “And I saw a new heaven and a new earth,” but the “new heaven and new earth” of Isaiah 65 is the Millennial Kingdom, whereas the new heaven and earth of Revelation 21 is the “Everlasting Kingdom,” the final heaven and earth.
There will be two kingdoms on earth in the future. The first will be Christ’s Millennial Kingdom, and it will last 1000 years (Rev. 20:1-5). It will be “new” because when Christ comes back, the earth—the soil, oceans, lakes, and air—will be completely restored to their pristine condition. When Christ comes from heaven he will fight the Battle of Armageddon and conquer the earth and set up his Millennial Kingdom on earth. But the earth will have been so polluted and ruined by thousands of years of human occupation and pollution that he will have to regenerate it into a Garden of Eden like state so people can live on it safely and joyfully. So the earth of Christ’s Millennial Kingdom really will be a “new heavens and earth” compared to what it is now. The total regeneration of the earth explains why Jesus spoke of a “New Beginning” in Matthew 19:28, and why in Acts 3:21, Peter said that Jesus will be in heaven until “the time all things are restored.” But the Millennial Kingdom and the earth at that time will come to an end after 1,000 years because of a war between God and the Devil, and the earth will be destroyed by fire (Rev. 20:7-10; 2 Peter 3:11-12). But after the war, God will again create a new heaven and new earth, which is briefly described in Revelation 21 and 22, and it is sometimes referred to as the “Everlasting Kingdom” because it will last forever.
We know this section in Isaiah is speaking of the Millennial Kingdom and not the final Everlasting Kingdom because of the earth it describes. For example, Isaiah 65:19 mentions the city of Jerusalem, and also there will still be people dying (Isa. 65:20).
[For more on the Millennial Kingdom, see Appendix 3, “Christ’s Future Kingdom on Earth. For more on why there will be natural people in the Millennial Kingdom who are born, marry, bear children, and die, see commentary on Matthew 25:32, the sheep and goat judgment].
“new heaven.” In the Hebrew text, the word “heaven” is plural, but it is always plural because there is no singular form of the noun in Hebrew; there is no word “heaven,” it is always “heavens.” The plural form is emphatic and points to the hugeness of “heaven,” which includes earth’s atmosphere and the sphere of God’s dwelling. Here is Isaiah there is no reason to believe that the “heaven” in which God dwells is going to be re-created when Christ conquers the earth, but the earth’s atmosphere will certainly be recreated and air pollution will be a thing of the past.