We are finishing the book of Isaiah today. The Lord talks about how His glory will be proclaimed to all nations, about how the nation of Israel will never disappear, and about how those who have hated Him will be judged.
The Lord says: "I will set a sign among them, and I will send some of those who survive to the nations---to Tarshish, to the Libyans and Lydians (famous as archers), to Tubal and Greece, and to the distant islands that have not heard of My fame or seen My glory. They will proclaim My glory among the nations." (Isaiah 66:19) The reference to "them" at the beginning of this verse is likely a reference to the Israelites. Christian scholars interpret the "sign" the Lord will send as a reference to Jesus Christ, whom He sent first to the nation of Israel. In that case we could paraphrase it like this: "I will set a sign (the Messiah, performing signs and wonders) among them, and I will send His disciples to the nations (to the Gentiles) who have not heard My name. Many people will believe in Christ and proclaim My glory to the nations (fulfilling the Great Commission in which Christ told believers to share the gospel with the whole world).
The reference to "they" in this next segment appears to be a reference to the Gentiles since a reference to "all your people" means the Jews. The Lord says: "'And they will bring all your people, from all the nations, to My holy mountain in Jerusalem as an offering to the Lord---on horses, in chariots and wagons, and on mules and camels,' says the Lord. 'They will bring them, as the Israelites bring their grain offerings, to the temple of the Lord in ceremonially clean vessels. And I will select some of them also to be priests and Levites,' says the Lord." (Isaiah 66:20-21) The Israelites, by and large, rejected Jesus as the Messiah and persecuted believers in Him. This is why the gospel message spread out so quickly and so far in the New Testament. The message went to the Gentile world where millions have believed in Christ since. But it will be Gentile believers who befriend and help Israel and who lead Israel to Christ.
When the Lord says, "I will select some of them also to be priests and Levites", this is understood by many Christians to mean Gentile believers. It would not have been lawful in the Bible era for Gentiles to be priests and Levites but through Christ the Lord will make one family of Jews and Gentiles (Galatians 3:28) and He has promised to make of all believers in Christ "a kingdom of priests" (Peter 2:9, Revelation 1:6) Everyone who has placed their faith in Christ is a child of God---everyone is equal in that family, whether Jew or Gentile.
Since the Lord intends to set up a new kingdom---an eternal kingdom---and since so many Gentiles will be a part of that kingdom, some of those to whom Isaiah's message was sent might have wondered if there would be any place left for them. The Lord assures the people of Israel that their nation and their descendants will always endure, up to the advent of the eternal kingdom and forever. "'As the new heavens and the new earth that I make will endure before Me,' declares the Lord, 'so will your name and descendants endure. From one New Moon to another and from one Sabbath to another, all mankind will come and bow down before Me,' says the Lord." (Isaiah 66:22-23) We have already discussed, earlier in Isaiah, the fact that the Lord will recreate the creation. All things will be made new, as the Lord says in the final book of the New Testament. The new creation, in which there will be no sin, will endure forever in complete perfection. There will be no one in that new creation who does not worship the Lord: "all mankind will come and bow down" before Him.
Even those who have hated and rejected Him must bow and declare He is God, before they are judged for their sins. The New Testament bears this out (Philippians 2:10-11) and Isaiah previously declared this fact in Chapter 45. They will confess that He is God because they cannot help it; the proof will be right there in front of them at His judgment seat. The book of Isaiah ends with a warning about judgment for those who rebel against God. He tells us that the righteous will see the bitter and terrible end that comes upon those who have hated God and who have hated God's children. "And they will go out and look on the dead bodies of those who rebelled against me; the worms that eat them will not die, the fire that burns them will not be quenched, and they will be loathsome to all mankind." (Isaiah 66:24)
I presume that these dead bodies are those who are slain in the final rebellion as described in the book of Revelation. The Lord Jesus Christ talked in Mark 9 about the fate of those who hated and rejected God, to their eternal peril and shame, stating that the worm never dies and the fire is never quenched.
Whether this indicates there is an actual burning hell is debatable among denominations but the Lord Jesus referred to this eternal state (separated from the goodness of God) by the ancient word "Gehenna", which was a reference to the Valley of Ben Hinnom outside of Jerusalem where the pagan Canaanites (and later some Israelites) sacrificed their children to idols. This rendered that area unclean for anything except refuse piles and a place to pile up carcasses of defeated enemies and of dead animals. What happens in refuse piles (landfills in today's world)? Maggots eat rotting things and fires are set to burn the trash. It is stated by a number of scholars that the Valley of Ben Hinnom was a landfill in Jesus' day and that He used this landfill as an example of a place of uncleanness and uselessness. It was a place of destruction. It was a place where no hope was left for the things deposited in it. In that sense, whether or not there is a literal burning hell, we know that eternal separation from God is a place where those who have lived useless, unclean lives will be consigned. It is a place where there is no hope for escape. Although it seems as if the book of Isaiah is ending on a dark note, it is a very necessary note to warn everyone that we do not want to go to a place without hope and light and love.