The Scriptures describe the coming Day of the Lord as sudden and unexpected, “like a thief in the night” (1 Thessalonians 5:2). This imagery underscores not only the swiftness of God’s intervention but also the unprepared state of those caught unaware. Jesus and the apostles consistently taught that vigilance and readiness are essential, for no one knows the exact day or hour (Matthew 24:36-44).
The Day of the Lord is a biblical term describing a time when God intervenes directly in human history to judge evil and vindicate His people. It was both judgment for the wicked and salvation for the faithful remnant. In the New Testament, it became synonymous with the return of Jesus. The moment when He comes again to judge the world, reward the faithful, and establish His kingdom.
Lessons from History: Noah and Jerusalem
History itself testifies to the cost of neglecting God’s warnings. In the days of Noah, people carried on with everyday life, such as eating, drinking, and marrying, and so on, until the flood came and “took them all away” (Matthew 24:39). The sudden judgment was not a surprise to Noah, who prepared according to God’s word. God warned Noah about the flood long before the flood came, and instructed him to build the ark. When the time came, God explicitly told Noah, “In seven days I will send rain” (Gen 7:4). Thus, Noah had both long-term preparation and short-term certainty. However, the flood swept away those who were unprepared.
Just like Noah, believers already know Christ will surely return. They also know that when the “beast” is revealed and a covenant of seven years is confirmed (Daniel 9:27), the final countdown begins. It will be seven years until the return of Christ, just as Noah was told seven days before the flood.
In 70 AD, Jerusalem and its temple were destroyed by the Romans. Jesus had foretold this event to his followers (Luke 21:5–6, Matthew 24:2), and those who heeded His warning escaped. But the unprepared perished. These examples serve as reminders that God’s judgment falls swiftly, and preparedness makes the difference between salvation and destruction.
Both Matthew 24:36–44 and 1 Thessalonians 5:2–4 capture this theme with striking similarity. Both passages show that God’s judgment and Christ’s return will interrupt ordinary life without warning. The faithful will not be caught off guard, but the unprepared will be overtaken by sudden disaster. Paul warns that while people say “peace and safety,” sudden destruction will come upon them. It will be sudden, unexpected, and will separate the prepared from the unprepared.
Behold, I come Quickly!
The book of Revelation amplifies this theme. In Revelation 22:12, Jesus declares, “Behold, I come quickly”. The word “quickly” or “soon” (in some translations) is derived from the Greek term “tachy,” which conveys suddenness rather than human notions of chronological immediacy or nearness. In other words, when it happens, it will be sudden and swift (judgment without delay).
Just as a thief arrives without notice, Christ’s judgment will break in decisively. For the unfaithful, His coming brings wrath (unexpected judgment); for those in Christ, it brings vindication and reward. The “thief” imagery and the promise of a sudden return serve as a warning to those who are not in Christ, and emphasize the urgency of constant readiness.
The Meaning of Being Left Behind
In Matthew 24:40–41, Jesus says, “Two men will be in the field; one will be taken and the other left.” It is here that clarity is needed against popular narratives. Fortunately, the flood account in the preceding verses provides the interpretive key: those “taken” were swept away in judgment, while those “left behind” were spared to live. To be “left behind” in this context is not a curse but a blessing. It signifies surviving judgment and entering into God’s promises. The faithful remain, but the unprepared are removed.
The Amplified version puts it so clearly: “At that time two men will be in the field; one will be taken [for judgment] and one will be left. Two women will be grinding at the mill; one will be taken [for judgment] and one will be left” (Matt 24: 40-41 AMP).
In Christ and Ready for His Appearing
The central issue, then, is being “in Christ.” Those who belong to Him are children of the light (1 Thessalonians 5:5). They are not overtaken by the day as a thief because they live in readiness, clothed in faith and obedience. Outside of Christ, you stand exposed to sudden judgment with no shelter.
God’s message to you and to every nation is this: Live ready. The day of the Lord will come suddenly, and neutrality is not an option. Just as in Noah’s generation and in first-century Jerusalem, judgment will separate the prepared from the unprepared. Christ’s coming quickly is not a matter of speculation about dates but of urgency in obedience. The warning is not meant to instill fear in you but to call you to faithfulness.
A faithful and wise steward is one who keeps doing what the master instructed, even when the master is absent (Matt 24:45-47). For when the master comes like a thief in the night, those who are in Him will not be shaken, but will stand secure, left to inherit the kingdom that was prepared for them.
