God is bringing the nations to judgment,

Isaiah 66:15-24
See, the Lord is coming with fire, and his chariots are like a whirlwind; he will bring down his anger with fury, and his rebuke with flames of fire.
“Those who consecrate and purify themselves to go into the gardens,following one who is among those who eat the flesh of pigs, rats and other unclean things—they will meet their end together with the one they follow,” declares the Lord.
“I will set a sign among them, and I will send some of those who survive to the nations. They will proclaim my glory among the nations.  And I will select some of them also to be priests and Levites,” says the Lord. The people from distant island that have no heard of my fame(名譽) or seen my glory.
From one New Moon to another and from one Sabbath to another, all mankind will come and bow down before me,” says the Lord. 
“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(討厭的) to all mankind.”
God is bringing the nations to judgment, Some he will spare, sending them to distant lands, to tell out his greatness to those who do not know him and to bring back those of his people still scattered abroad.
The final bright picture of Jerusalem, visited by pilgrims of all nations coming to worship God has its dark shadow side in the fate of those who refuse God's mercy.
Why?
God created a new heaven and wonder land to his people. There are pilgrims have mercy from the Lord, they will be priest and Levites to serve the Lord, so the gospel will preaches to the world, all nations.
Those who consecrate and purify themselves are Christians, it they still follow the world to do unclean things, they will be judged at end.
How terrible of the end judgment to those who rebelled against me; the worms that eat them will not die, the fire that burns them will not be quenched.
How?
Fear the Lord and knowing the consequence of what we are doing now!