1 The word that Isaiah the son of Amoz saw concerning Judah and Jerusalem.
2 And it shall come to pass in the last days, that the mountain of the LORD's house shall be established in the top of the mountains, and shall be exalted above the hills; and all nations shall flow unto it.
In the last days of Judah, she was the center of trade for the region with all countries traveling to her to do trade.
3 And many people shall go and say, “Come ye, and let us go up to the mountain of the LORD, to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for out of Zion shall go forth the law, and the word of the LORD from Jerusalem.
Many, many people at this time converted to Judaism and learned about the One True God.
After Jesus' Crucifixion, the Gospel spread to every nation and people from every language now say ”Let us worship God.”
4 And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruning-hooks: nation shall not lift up sword against nation, neither shall they learn war any more.
Isaiah wrote this during a time when the Assyrian army is marching throughout the land conquering people. There is war everywhere.
Jesus came during the great Pax Romana; the Roman Peace. This was a time when war was rare because the Empire kept order. They pretty much left each nation alone as long as they didn’t rebel, cause problems with their neighbors, and paid their taxes. So the common man had no reason to learn the skills of war. This Pax Romana was still in effect when Judah rebelled against Rome and was destroyed (AD70).
Of course, this is also the time Christ set up His kingdom; a kingdom where its citizens don’t fight with swords and spears, but with prayer, praise and the Word of God.
5 O house of Jacob, come ye, and let us walk in the light of the LORD.
Now switching from speaking to Judah to speaking to God....
6 Therefore thou hast forsaken thy people the house of Jacob, because they be replenished from the east, and are soothsayers like the Philistines, and they please themselves in the children of strangers.
The descendants of Jacob have chosen to follow the religion and practices of their pagan neighbors instead of the one true God.
7 Their land also is full of silver and gold, neither is there any end of their treasures; their land is also full of horses, neither is there any end of their chariots:
Israel and Judah have become very rich. This often interferes with a person's walk with God. When people don't have physical needs, they have a harder times seeing how they need God.
8 Their land also is full of idols; they worship the work of their own hands, that which their own fingers have made:
9 And the mean man boweth down, and the great man humbleth himself: therefore forgive them not.
The Jew’s rebellion against God is what opened the door to salvation for the rest of the world. Those unbelieving Jews were kicked out of “Israel” and the believers from all other nations were added to it.
10 Enter into the rock, and hide thee in the dust, for fear of the LORD, and for the glory of his majesty.
The rock is Jesus and the only way to salvation is through Him. Those before the cross looked forward to His appearing. We look back.
11 The lofty looks of man shall be humbled, and the haughtiness of men shall be bowed down, and the LORD alone shall be exalted in that day.
"That Day" is the day God uses foreign armies to punish the unbelieving Jews.
12 For the day of the LORD of hosts shall be upon every one that is proud and lofty, and upon every one that is lifted up; and he shall be brought low:
God will humble anyone who is proud and lofty, who thinks himself better than he is. "The Day of the Lord" arrives for all sinners eventually. In this case, God will destroy the Jews for their disobedience.
13 And upon all the cedars of Lebanon, that are high and lifted up, and upon all the oaks of Bashan,
The Jews thought themselves to be as strong and everlasting as the great forest in their area.
14 And upon all the high mountains, and upon all the hills that are lifted up,
15 And upon every high tower, and upon every fenced wall,
16 And upon all the ships of Tarshish, and upon all pleasant pictures.
17 And the loftiness of man shall be bowed down, and the haughtiness of men shall be made low: and the LORD alone shall be exalted in that day.
Destruction of Israel by the Assyrians and Judah by the Babylonians.
18 And the idols He shall utterly abolish.
Idol worship in Judea will end one way or another. If the people don't repent and turn to the True God, God will remove the people from the land.
19 And they shall go into the holes of the rocks, and into the caves of the earth, for fear of the LORD, and for the glory of His majesty, when He ariseth to shake terribly the earth.
The people tried to hide when the enemies attacked the land, but because they were sent from God, hiding won't do any good.
20 In that day a man shall cast his idols of silver, and his idols of gold, which they made each one for himself to worship, to the moles and to the bats;
21 To go into the clefts of the rocks, and into the tops of the ragged rocks, for fear of the LORD, and for the glory of His majesty, when He ariseth to shake terribly the earth.
22 Cease ye from man, whose breath is in his nostrils: for wherein is he to be accounted of?
Human beings are nothing compared to God, and no matter how important they think they are, God will triumph.