“The day of the Lord holds an important place in prophecy. Old Testament prophets declared that it signaled judgment for Israel. Several prophets referred to it as God’s day of judgment upon individual nations, such as Babylon, Egypt, Edom, and others. Zechariah 14:1-4 explains that the events pertaining to Christ’s second advent are included in the day of the Lord” (note on 1 Thessalonians 5:2). This passage states:

Behold, a day is coming for the Lord, when the spoil taken from you will be divided in your midst. For I will gather all the nations against Jerusalem to battle, and the city shall be taken and the houses plundered and the women raped. Half of the city shall go out into exile, but the rest of the people shall not be cut off from the city. Then the Lord will go out and fight against those nations as when he fights on a day of battle. On that day his feet shall stand on the Mount of Olives that lies before Jerusalem on the east, and the Mount of Olives shall be split in two from east to west by a very wide valley, so that one half of the Mount shall move northward, and the other half southward. (Zechariah 14:1-4)

Paul’s focus on the day of the Lord in his first letter to the Thessalonians was in the context of Christ’s return (1 Thessalonians 4:13-18). Paul said that it “will come like a thief in the night” (1 Thessalonians 5:2). If the day of the Lord began after Christ’s second advent, “it could not come as a ‘thief in the night,’ unexpected and unheralded, since that particular advent is accompanied by signs (Matthew 24:30, 31). Consequently, the only way these events could occur unexpectedly would be for them to begin immediately after the rapture of the church. The day of the Lord, therefore, is that extended period of time when God will deal with Israel after the rapture of the church. It will continue through the second advent and the millennial age, which precedes the creation of the new heaven and new earth. God will actively intervene throughout the time period to punish sin” (note on 1 Thessalonians 5:2).

Isaiah’s prophesy about the day of the Lord made it clear that the Lord will establish his exalted position on the earth (Isaiah 2:11) and he will at that time rid the world of all idol worship (Isaiah 2:20). Isaiah said:

For the Lord of hosts has a day
    against all that is proud and lofty,
    against all that is lifted up—and it shall be brought low…
And the haughtiness of man shall be humbled,
    and the lofty pride of men shall be brought low,
    and the Lord alone will be exalted in that day.
And the idols shall utterly pass away.
And people shall enter the caves of the rocks
    and the holes of the ground,
from before the terror of the Lord,
    and from the splendor of his majesty,
    when he rises to terrify the earth. (Isaiah 2:12-19)

The title used in Isaiah 2:12, LORD of Hosts refers to God’s position of leadership over both human and heavenly armies and therefore, signifies Christ’s intention of conquering the world when he returns to earth. Isaiah’s statement, “And the haughtiness of man shall be humbled; and the lofty pride of man shall be brought low” (Isaiah 2:17) suggests that mankind’s usurping of God’s authority is the main driver behind God’s use of force to regain control of the world that he created and which rightfully belongs to him.

Jesus’ disciples and others whom he taught did not completely understand the purpose of the day of the Lord, nor did they initially comprehend the reason for the removal of Christians before it began. Jesus used parables to describe the events that were going to take place (Matthew 21:33-22:14) and only explained certain details to his twelve apostles before his death (Matthew 24:15-31). On one occasion, Jesus responded to a question from the Pharisees about when the kingdom of God would come by telling them it had already arrived. Then, Jesus told his disciples what to expect at the time of his second coming. Jesus said:

“The kingdom of God is not coming in ways that can be observed, nor will they say, ‘Look, here it is!’ or ‘There!’ for behold, the kingdom of God is in the midst of you.”

And he said to the disciples, “The days are coming when you will desire to see one of the days of the Son of Man, and you will not see it. And they will say to you, ‘Look, there!’ or ‘Look, here!’ Do not go out or follow them. For as the lightning flashes and lights up the sky from one side to the other, so will the Son of Man be in his day. But first he must suffer many things and be rejected by this generation. Just as it was in the days of Noah, so will it be in the days of the Son of Man. They were eating and drinking and marrying and being given in marriage, until the day when Noah entered the ark, and the flood came and destroyed them all. Likewise, just as it was in the days of Lot—they were eating and drinking, buying and selling, planting and building, but on the day when Lot went out from Sodom, fire and sulfur rained from heaven and destroyed them all—so will it be on the day when the Son of Man is revealed. On that day, let the one who is on the housetop, with his goods in the house, not come down to take them away, and likewise let the one who is in the field not turn back. Remember Lot’s wife. Whoever seeks to preserve his life will lose it, but whoever loses his life will keep it. I tell you, in that night there will be two in one bed. One will be taken and the other left. There will be two women grinding together. One will be taken and the other left.” And they said to him, “Where, Lord?” He said to them, “Where the corpse is, there the vultures will gather.” (Luke 17:20-37)

Paul’s statement that the Lord would come like a thief in the night (1 Thessalonians 5:2) echoed Jesus’ sentiment that people will be caught off guard in the days of the Son of Man (Luke 17:24). Jesus compared the initiation of the day of the Lord to the days of Noah and the days of Lot when God destroyed everyone. Paul said, “While people are saying, ‘There is peace and security.’ Then sudden destruction will come upon them as labor pains come upon a pregnant woman, and they will not escape” (1Thessalonians 5:3).

Unlike the Jews who were warned about the sudden destruction that was awaiting them in the day of the Lord, believers in Christ welcomed Jesus’ return and expected the day of the Lord to be a time of great celebration. Paul described the event as a moment of immediate transformation that would result in immortality. Paul said, “I tell you this, brothers, flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable. Behold! I tell you a mystery. We shall not all sleep, but we shall all be changed, in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised imperishable, and we shall be changed” (1 Corinthians 15:50-52). The Greek word that is translated changed, allasso (al-lasˊ-so) means “to make different…to change for the better” (G236). Allasso also appears in Hebrews 1:11-12 where the final destruction of the earth is described. Quoting from Psalm 102:25-27, the writer states, “You, Lord, laid the foundation of the earth in the beginning, and the heavens are the work of your hands; they will perish, but you remain; they will all wear out like a garment, like a robe you will roll them up, like a garment they will be changed.”

“God did not intend for the earth to be eternal…the most graphic account of the end of the entire physical universe is found in 2 Peter 3:10” (note on Genesis 8:21-22). Peter’s account of the day of the Lord focused on the destruction of the ungodly. Peter said scoffers will come in the last days, “following their own sinful desires. They will say, ‘Where is the promise of his coming? For ever since the fathers fell asleep, all things are continuing as they were from the beginning of creation. For they deliberately overlook this fact, that the heavens existed long ago, and the earth was formed out of water and through water by the word of God, and that by means of these the world that existed was deluged with water and perished. But by the same word the heavens and the earth that now exists are stored up for fire, being kept until the day of judgment and destruction of the ungodly” (2 Peter 3:3-7). Peter cautioned believers to not overlook the fact that God’s timing is not the same as ours. Peter said, “The Lord is not slow to fulfill his promise as some count slowness, but is patient toward you, not wishing that any should perish, but that all should reach repentance” (2 Peter 3:9).

Peter concluded his discussion of the day of the Lord by refocusing his readers’ attention from the bad news to the good news of Christ’s return. Second Peter 3:11-13 states, “Since all these things are thus to be dissolved, what sort of people ought you to be in lives of holiness and godliness, waiting and hastening the coming of the day of God, because of which the heavens will be set on fire and dissolved, and the heavenly bodies will melt as they burn! But according to his promise we are waiting for new heavens and a new earth in which righteousness dwells.” Revelation 21:1 tells us that a new heaven and new earth will be created after the great white throne judgment (Revelation 20:11-15). “The new heaven and the new earth are not duplicates of the heaven and earth that now exist. The word ‘new’ is a translation of the Greek word kainon (2537), which means ‘qualitatively new.’ To some, this suggests that the new earth will be as the current earth was at its creation” (note on Revelation 21:1-22:5). The connection between believers being changed (allasso, 1 Corinthians 15:51) and the earth being changed (allasso, Hebrews 1:12) suggests though, that there will be at least one difference between the current earth and the new one. The new earth will be imperishable. Paul said, “When the perishable puts on the imperishable, and the mortal puts on immortality, then shall come to pass the saying that is written: ‘Death is swallowed up in victory’” (1 Corinthians 15:54).