Written many centuries ago, the book of "the minor prophet" Joel (as it is often referred to - an unfair and inaccurate label based upon its relative shortness) is nevertheless ultra-modern because most of what is prophesied is yet to happen, at the time of Christ's return. It is a book of spectacular events, encouragements and warnings that, although originally delivered to the people of Judah, is actually describing the whole of humanity in the end time (see The End Of The World? to understand just what it is that Christ is returning to put an end to).
"1:1 The word of the LORD that came to Joel the son of Pethuel. 1:2 Hear this, ye old men, and give ear, all ye inhabitants of the land. Hath this been in your days, or even in the days of your fathers? 1:3 Tell ye your children of it, and let your children tell their children, and their children another generation. 1:4 That which the palmerworm hath left hath the Locust eaten; and that which the locust hath left hath the cankerworm eaten; and that which the cankerworm hath left hath the caterpillar eaten.
The message (and purpose) of The Lord's Prophets wasn't to proclaim that God's wrath is coming; it was to warn that God's wrath is coming if you don't repent.
1:13 Gird yourselves, and lament, ye priests: howl, ye ministers of the altar: come, lie all night in sackcloth, ye ministers of my God: for the meat offering and the drink offering is withholden from the house of your God. 1:14 Sanctify ye a fast, call a solemn assembly, gather the elders and all the inhabitants of the land into the house of the LORD your God, and cry unto the LORD.
Joel Chapter 2
"Locusts" (i.e. literal insects) don't and can't fly from mountaintop to mountaintop, spewing lethal fire and destruction upon people below. Modern-day war "locusts" can, and do: "2:5 Like the noise of chariots on the tops of mountains shall they leap, like the noise of a flame of fire that devoureth the stubble, as a strong people set in battle array" (Joel 2:5 KJV). That is the reason that Christ will return with overwhelming power of His own, to annihilate man's capability to make war (see Christ the Conqueror For Peace and The Coming World Dictator).
"2:1 Blow ye the trumpet in Zion [see Who, What or Where Is Zion?], and sound an alarm in my holy mountain: let all the inhabitants of the land tremble: for the day of the LORD cometh, for it is nigh at hand; 2:2 A day of darkness and of gloominess, a day of clouds and of thick darkness, as the morning spread upon the mountains: a great people and a strong; there hath not been ever the like, neither shall be any more after it, even to the years of many generations. 2:3 A fire devoureth before them; and behind them a flame burneth: the land is as the garden of Eden before them, and behind them a desolate wilderness; yea, and nothing shall escape them. 2:4 The appearance of them is as the appearance of horses; and as horsemen, so shall they run. 2:5 Like the noise of chariots on the tops of mountains shall they leap, like the noise of a flame of fire that devoureth the stubble, as a strong people set in battle array. 2:6 Before their face the people shall be much pained: all faces shall gather blackness. 2:7 They shall run like mighty men; they shall climb the wall like men of war; and they shall march every one on his ways, and they shall not break their ranks: 2:8 Neither shall one thrust another; they shall walk every one in his path: and when they fall upon the sword, they shall not be wounded. 2:9 They shall run to and fro in the city; they shall run upon the wall, they shall climb up upon the houses; they shall enter in at the windows like a thief.
Repentance is the only way that The Lord's wrath can be avoided.
2:12 Therefore also now, saith the LORD, turn ye even to me with all your heart, and with fasting, and with weeping, and with mourning: 2:13 And rend your heart, and not your garments, and turn unto the LORD your God: for he is gracious and merciful, slow to anger, and of great kindness, and repenteth him of the evil. 2:14 Who knoweth if he will return and repent, and leave a blessing behind him; even a meat offering and a drink offering unto the LORD your God?
"2:18 Then will the LORD be jealous for his land, and pity his people" (Joel 2:18 KJV) speaks of anyone, anywhere, who repents and obeys Him because at that time all the world will be subject to and within the Kingdom of God i.e. "4:1 But in the last days it shall come to pass, that the mountain of the house of the LORD shall be established in the top of the mountains, and it shall be exalted above the hills; and people shall flow unto it. 4:2 And many nations shall come, and say, Come, and let us go up to the mountain of the LORD, and to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for the law shall go forth of Zion, and the word of the LORD from Jerusalem. 4:3 And he shall judge among many people, and rebuke strong nations afar off; and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up a sword against nation, neither shall they learn war any more" (Micah 4:1-3 KJV).
2:18 Then will the LORD be jealous for his land, and pity his people [see Why Is The Lord Jealous?].
"2:28 And it shall come to pass afterward, that I will pour out my spirit upon all flesh" (Joel 2:28 KJV) will be The Cure For The Carnal Mind of man.
2:28 And it shall come to pass afterward, that I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions: 2:29 And also upon the servants and upon the handmaids in those days will I pour out my spirit. 2:30 And I will show wonders in the heavens and in the earth, blood, and fire, and pillars of smoke. 2:31 The sun shall be turned into darkness, and the moon into blood, before the great and the terrible day of the LORD come. 2:32 And it shall come to pass, that whosoever shall call on the name of the LORD shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the LORD hath said, and in the remnant whom the LORD shall call." (Joel 2:28-32 KJV)
Joel Chapter 3
"3:14 Multitudes, multitudes in the valley of decision: for the day of the LORD is near in the valley of decision. 3:15 The sun and the moon shall be darkened, and the stars shall withdraw their shining. 3:16 The LORD also shall roar out of Zion, and utter his voice from Jerusalem; and the heavens and the earth shall shake: but the LORD will be the hope of his people" (Joel 3:14-16 KJV) refers to The Battle of Armageddon. The Valley of Jehoshaphat came to be used for the valley between the city of Jerusalem and The Mount Of Olives (shown in the photo).
"3:1 For, behold, in those days, and in that time, when I shall bring again the captivity of Judah and Jerusalem, 3:2 I will also gather all nations, and will bring them down into the valley of Jehoshaphat, and will plead with them there for my people and for my heritage Israel, whom they have scattered among the nations, and parted my land. 3:3 And they have cast lots for my people; and have given a boy for an harlot, and sold a girl for wine, that they might drink.
3:17 So shall ye know that I am the LORD your God dwelling in Zion [see Zionism], my holy mountain: then shall Jerusalem be holy, and there shall no strangers pass through her any more. 3:18 And it shall come to pass in that day, that the mountains shall drop down new wine, and the hills shall flow with milk, and all the rivers of Judah shall flow with waters, and a fountain shall come forth of the house of the LORD, and shall water the valley of Shittim. 3:19 Egypt shall be a desolation, and Edom shall be a desolate wilderness, for the violence against the children of Judah, because they have shed innocent blood in their land. 3:20 But Judah shall dwell for ever, and Jerusalem from generation to generation. 3:21 For I will cleanse their blood that I have not cleansed: for the LORD dwelleth in Zion." (Joel 3:17-21 KJV)