Isaiah tells us that through calamities and violence most of the world will be depopulated.

Behold, the day of the LORD cometh, cruel both with wrath and fierce anger, to lay the land desolate: and he shall destroy the sinners thereof out of it…. I will make a man more precious [rare] than fine gold; even a man than the golden wedge of Ophir. (Isa. 13:9, 12; translation in brackets added).

Therefore hath the curse devoured the earth, and they that dwell therein are desolate: therefore the inhabitants of the earth are burned, and few men left (Isa. 24:6).

The Lord says that he will raise up his hand of destruction, his “ax,” saw,” and “the rod of mine anger” to humble a “hypocritical nation” (Isa. 10:5-6, 15). This is referring to a nation containing the covenant people, a sizable portion of whom have rebelled against God’s prophet and earned the Lord’s wrath (3 Ne. 21: 9-11). Also by this time most of the gentiles in this nation will have rejected the God of this land (Eth. 2:10), making them ripe for destruction (Mos. 29:26-27). As the Lord spoke through Joseph Smith:

And the anger of the Lord is kindled, and his sword is bathed in heaven, and it shall fall upon the inhabitants of the earth. And the arm of the Lord shall be revealed; and the day cometh that they who will not hear the voice of the Lord, neither the voice of his servants, neither give heed to the words of the prophets and apostles, shall be cut off from among the people; For they have strayed from mine ordinances, and have broken mine everlasting covenant; They seek not the Lord to establish his righteousness, but every man walketh in his own way, and after the image of his own god, whose image is in the likeness of the world, and whose substance is that of an idol, which waxeth old and shall perish in Babylon, even Babylon the great, which shall fall (D&C 1:13-16).

This condemnation prophesies Babylon’s fall, but it also indicts those who have “strayed from mine ordinances, and have broken mine everlasting covenant.” Through the use of historical types, Isaiah prophesies that after the Assyrian’s armies have humbled covenant Israel, and then after the tyrant himself has been turned back at Zion (Isa. 37:32-34), he will unleash his anger upon the world at large—on Babylon. The frenzy of his anger will be awesome, and the slaughter of millions will erase entire nations (Isa. 10:7, 13-14; 14:6; 17:13; 33:3; 34:2; 60:12). Some of Isaiah’s terms even suggest the possibility of nuclear weapons in the widespread destruction. (He says that wickedness will burn, devouring entire populations and that the fire will “billow upward in mushrooming clouds of smoke” [Isa. 9:18, Gileadi translation]). Given the weapons available in the world, the annihilation of countries is not unimaginable, and after the resulting fallout has darkened the globe, many more may die of starvation and illness. As Isaiah states: “And in that day they shall roar against them like the roaring of the sea: and if one look unto the land, behold darkness and sorrow, and the light is darkened in the heavens thereof” (Isa. 5:30).

God will yet show that he who lives by the sword will die by the sword—and those who refuse to take up arms will have a choice to make: “And it shall come to pass among the wicked, that every man that will not take up his sword against his neighbor must needs flee unto Zion for safety” (D&C 45:68). For many, however, the desperate question will be, “where is Zion?”

Again, it must be stressed that destruction on this scale does not occur until after the Assyrian tyrant has made his appearance on the world stage, and according to Isaiah’s timeline this won’t happen until after massive earthquakes and internecine wars have weakened the people—specifically, the people in a nation where the Lord’s house is “established in the top of the mountains” (Isa. 2:2).