Joel 2:4

Joel 2:4 says, The appearance of them is as the appearance of horses; and as horsemen, so shall they run.  The coming locusts and caterpillars were going to look like an invading army.  When God's judgment comes, there can be little doubt that it is His work.  Insects do not just suddenly grow this large.  Matthew Henry points out that extraordinary judgments of God are very rare, since He chooses to show mercy whenever possible.  Still, when people refuse to accept God's mercy, they can be certain of His judgment.  The next few verses continue to speak of the power of the devastating swarm. Verse five adds, 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.  Verse six continues, Before their face the people shall be much pained: all faces shall gather blackness.  Verse seven states, 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:  Verse eight adds, 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.  Verse nine continues, 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.  Verse ten concludes, The earth shall quake before them; the heavens shall tremble: the sun and the moon shall be dark, and the stars shall withdraw their shining:  What Joel was telling the people of Judah was that the devastation was to be complete, and they would be powerless to stop it.  God doesn't need armies to destroy those who rebel against Him, nor will any army be strong enough to protect us against His wrath. When Judah sought peace and security in the things of this world instead of in God, God used the simple things of this world to remind them that He has control of everything in the world.  We might ask if that is the case why God doesn't just destroy all evil and cause everyone to follow Him.  The answer once again is free will.  God wants people to follow Him through a willing faith.  He promises us that He will be with us through all trials and tribulations, but also allows us to choose to ignore following His leadership.  When devastation comes, it is not because of God's desire to punish people, but because of their refusal to accept His forgiveness through faith.