The brief, prophetic book of Joel contains one of the clearest descriptions of a future judgment that is referred to as the Day of the Lord. “The expression, common among the prophets, refers to a time of God’s intervention to judge his enemies and save his people. It is used of specific interventions in history but also of God’s final intervention at the end of the age, and it is equated in the New Testament with the day of Christ’s return (1 Thes 5:1-4; 2 Pet 3:8-13)” (Joel, The Spiritual Growth Bible, p. 985). Jesus told his disciples, “But concerning that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only. For as were the days of Noah, so will be the coming of the Son of Man. For as in those days before the flood they were eating and drinking, marrying and giving in marriage, until the day when Noah entered the ark, and they were unaware until the flood came and swept them all away, so will be the coming of the Son of Man” (Matthew 24:36-39).

Joel’s message about the Day of the Lord had two parts to it. First Joel talked about the positive side of this important event. Joel 2:18-27 “speaks of God’s future work of restoring the land. The Lord will take pity on his people and will remove the plagues by which he punished them (v. 25, Is 40:1, 2). Then they, as well as the entire world, will know that God is in their midst (cf. Ezek. 48:35)” (note on Joel 2:18-27). Joel prophesied, “The threshing floors shall be full of grain; the vats shall overflow with wine and oil. I will restore to you the years that the swarming locust has eaten, the hopper, the destroyer, and the cutter, my great army, which I sent among you” (Joel 2:24-25). Joel’s description of the various types of locusts that would bring destruction upon the land as God’s great army coincided with the events that took place prior to the exiles of both Israel and Judah. God’s promise that he would restore their land meant that the people would have hope for the future even though they had to suffer temporarily.

Joel’s prophesy about God’s judgment of the nations revealed the dark side of the Day of the Lord. In this section of Joel’s prophecy we see the calling to arms of the nations and preparation for a war that will be led by Antichrist, “the future political ruler who will oppose God and those who follow him” (Revelation 13:6, 7). The location where the conflict will take place is referred to by Joel as the valley of decision. Joel prophesied:

Hasten and come,
    all you surrounding nations,
    and gather yourselves there.
Bring down your warriors, O Lord.
Let the nations stir themselves up
    and come up to the Valley of Jehoshaphat;
for there I will sit to judge
    all the surrounding nations.

Put in the sickle,
    for the harvest is ripe.
Go in, tread,
    for the winepress is full.
The vats overflow,
    for their evil is great.

Multitudes, multitudes,
    in the valley of decision!
For the day of the Lord is near
    in the valley of decision.
The sun and the moon are darkened,
    and the stars withdraw their shining.

The Hebrew words that are translated valley of decision, suggest that this is a manmade trench where people have essentially dug their own graves through their rebellion against God. What we know from the book of Revelation is that those who follow Antichrist into the valley of decision have sworn allegiance to him in exchange for being able to buy and sell goods during the Great Tribulation (Revelation 13:16). These people will be cast into the lake of fire after they are judged according to what they have done (Revelation 14:9-11, 20:11-15).

“Since the prophets linked the Day of the Lord with the Messiah’s coming, it was natural for Jesus and the early church to associate it with his return at the end of the age (John 6:40; 1 Thes 5:4-10; 2 Tim 4:8; 2 Pet 3:10-13). The preoccupation of the New Testament is not, like so often today, with when that day will be but rather with the importance of being ready for it and being active in the Lord’s work in the meantime (Matt 24:42-25:46; 1 Thes 5:11; 2 Pet 3:10-14). Jesus’ parable of the ten virgins (Matthew 25:1-13) and parable of the talents (Matthew 25:14-30) make it clear that not everyone who calls themselves a Christian will inherit the kingdom of heaven. In his depiction of the final judgment (Matthew 25-31-46), Jesus indicated there were two groups that were separated based on their actions. Those who did not identify themselves with Christ during the Great Tribulation by ministering to the needs of the 144,000 Jews tasked with preaching the gospel and those who did. This example shows us that actions speak louder than words when it comes to demonstrating our faith to those around us and when the Day of the Lord arrives, every action will matter (Matthew 25:45-46).