What is the "Day of the Lord"? Is it a single day or a designation for a period of time? Is it a good event or a fearful one? Did it already occur or is it still yet in the future? Does the "Day of the Lord" have the same meaning between the Old and New Testaments?

Introduced by major and minor prophets and influenced by God's intervention in Israel's early conflicts, the phrase "Day of the Lord" was used to place an emphasis on the swift and decisive nature of God's victory over His enemies. Scholars believe that the idea was influenced by perceptions prevalent during the Ancient Near East that a mighty warrior – king can consummate an entire military campaign in a single day.

Hebrew: Yôm YHWH

When examining all instances of the "Day of the Lord" in the Old Testament, the phrase is used to denote a future event, which can occur later as a historical event or as a reference to an eschatological event that will culminate the present age. Several additional observations can be made as well:

In cases where the prophetic "Day of the Lord" is fulfilled by a historical event, it becomes apparent that the "Day of the Lord" took place over a period of time instead of a single 24 hour day.

Some prophets may speak of the "Day of the Lord" with a reference to the same future historical event, and it could be in the near future (less than 100 years), distant future or eschatological future.

The "Day of the Lord" is a reference to divine judgment; it can be God's judgment of people or a nation including the nation of Israel.

When God made the Mosaic Covenant, He warns the nation of Israel that, if they disobeyed, their punishment could include conquest by foreigners, exile from the land, and scattered about the earth (Deut 28:15-64); thus, God's judgment was not arbitrary and avoidable.

While the "Day of the Lord" is a period of judgment, it is also associated with restoration and described with terms like healing, hope and joy. Often, when in reference to the eschatological future, the "Day of the Lord" is a deliverance of the regathered and repentant Israel.

The following chart attempts to observe the prophecies of the "Day of the Lord" with the benefit of the hindsight of history.

The following chart attempts to observe the prophecies of the "Day of the Lord" with a view towards the eschatological future.

Greek: hēmera kyriou

Throughout the Old Testament, the "Day of the Lord" was in context of YHWH; however, with the exception of his reference to Joel's prophecy in Acts 2:20, Peter spoke of the "Day of the Lord," "Day of Judgment," and the "Day of God" synonymously in the context of Jesus Christ.

Then the Lord knows how to rescue the godly from temptation, and to keep the unrighteous under punishment for the day of judgment, and especially those who indulge the flesh in its corrupt desires and despise authority. (2 Pet 2:9-10)

Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts, and saying, "Where is the promise of His coming? For ever since the fathers fell asleep, all continues just as it was from the beginning of creation." For when they maintain this, it escapes their notice that by the word of God the heavens existed long ago and the earth was formed out of water and by water, through which the world at that time was destroyed, being flooded with water. But by His word the present heavens and earth are being reserved for fire, kept for the day of judgment and destruction of ungodly men. But do not let this one fact escape your notice, beloved, that with the Lord one day is like a thousand years, and a thousand years like one day. The Lord is not slow about His promise, as some count slowness, but is patient toward you, not wishing for any to perish but for all to come to repentance. But the day of the Lord will come like a thief, in which the heavens will pass away with a roar and the elements will be destroyed with intense heat, and the earth and its works will be burned up. Since all these things are to be destroyed in this way, what sort of people ought you to be in holy conduct and godliness, looking for and hastening the coming of the day of God, because of which the heavens will be destroyed by burning, and the elements will melt with intense heat! But according to His promise we are looking for new heavens and a new earth, in which righteousness dwells. Therefore, beloved, since you look for these things, be diligent to be found by Him in peace, spotless and blameless, and regard the patience of our Lord as salvation; just as also our beloved brother Paul, according to the wisdom given him, wrote to you, as also in all his letters, speaking in them of these things, in which are some things hard to understand, which the untaught and unstable distort, as they do also the rest of the Scriptures, to their own destruction. You therefore, beloved, knowing this beforehand, be on your guard so that you are not carried away by the error of unprincipled men and fall from your own steadfastness, but grow in the grace and knowledge of our Lord and Savior Jesus Christ. To Him be the glory, both now and to the day of eternity. Amen. (2 Pet 3:3-18)

Paul describes the second coming of Jesus Christ as sudden and unannounced. It will herald a time of punishment for non-Believers for their guilt of sin and a time of confirmation for those who placed their faith in Jesus Christ as atonement for their sins. Paul writes of this terrible day to inform Christians that judgment is in the future, and encourages them to remain steadfast and continue growing in their faith.

I thank my God always concerning you for the grace of God which was given you in Christ Jesus, that in everything you were enriched in Him, in all speech and all knowledge, even as the testimony concerning Christ was confirmed in you, so that you are not lacking in any gift, awaiting eagerly the revelation of our Lord Jesus Christ, who will also confirm you to the end, blameless in the day of our Lord Jesus Christ. (1 Cor 1:8)

I have decided to deliver such a one to Satan for the destruction of his flesh, so that his spirit may be saved in the day of the Lord Jesus. (1 Cor 5:5)

For we write nothing else to you than what you read and understand, and I hope you will understand until the end; just as you also partially did understand us, that we are your reason to be proud as you also are ours, in the day of our Lord Jesus. (2 Cor 1:13-14)

For I am confident of this very thing, that He who began a good work in you will perfect it until the day of Christ Jesus. For it is only right for me to feel this way about you all, because I have you in my heart, since both in my imprisonment and in the defense and confirmation of the gospel, you all are partakers of grace with me. For God is my witness, how I long for you all with the affection of Christ Jesus. And this I pray, that your love may abound still more and more in real knowledge and all discernment, so that you may approve the things that are excellent, in order to be sincere and blameless until the day of Christ; having been filled with the fruit of righteousness which comes through Jesus Christ, to the glory and praise of God. (Phil 1:6-11)

Now as to the times and the epochs, brethren, you have no need of anything to be written to you. For you yourselves know full well that the day of the Lord will come just like a thief in the night. While they are saying, "Peace and safety!" then destruction will come upon them suddenly like labor pains upon a woman with child, and they will not escape. But you, brethren, are not in darkness, that the day would overtake you like a thief; for you are all sons of light and sons of day. We are not of night nor of darkness; so then let us not sleep as others do, but let us be alert and sober. (1 Thess 5:1-6)

Now we request you, brethren, with regard to the coming of our Lord Jesus Christ and our gathering together to Him, that you not be quickly shaken from your composure or be disturbed either by a spirit or a message or a letter as if from us, to the effect that the day of the Lord has come. (2 Thess 2:1-2)

I have fought the good fight, I have finished the course, I have kept the faith; in the future there is laid up for me the crown of righteousness, which the Lord, the righteous Judge, will award to me on that day; and not only to me, but also to all who have loved His appearing. (2 Tim 4:7-8)

Omitting any reference to the "Day of the Lord," Jesus only speaks of the "Day of Judgment," and it is directed to non-Believers and in the context of Final Judgment.

Whoever does not receive you, nor heed your words, as you go out of that house or that city, shake the dust off your feet. Truly I say to you, it will be more tolerable for the land of Sodom and Gomorrah in the day of judgment than for that city. (Matt 10:14-15)

Then He began to denounce the cities in which most of His miracles were done, because they did not repent. "Woe to you, Chorazin! Woe to you, Bethsaida! For if the miracles had occurred in Tyre and Sidon which occurred in you, they would have repented long ago in sackcloth and ashes. Nevertheless I say to you, it will be more tolerable for Tyre and Sidon in the day of judgment than for you. And you, Capernaum, will not be exalted to heaven, will you? You will descend to Hades; for if the miracles had occurred in Sodom which occurred in you, it would have remained to this day. Nevertheless I say to you that it will be more tolerable for the land of Sodom in the day of judgment, than for you." (Matt 11:20-24; Luke 10:10-16)

Either make the tree good and its fruit good, or make the tree bad and its fruit bad; for the tree is known by its fruit. You brood of vipers, how can you, being evil, speak what is good? For the mouth speaks out of that which fills the heart. The good man brings out of his good treasure what is good; and the evil man brings out of his evil treasure what is evil. But I tell you that every careless word that people speak, they shall give an accounting for it in the day of judgment. For by your words you will be justified, and by your words you will be condemned. (Matt 12:33-37)

Between the Old and the New Testaments, the phrase "Day of the Lord" appears to have different purposes.

While the Old Testament "Day of the Lord" was a message of punishment, God used His prophets to bring His people to repentance and return to their covenant relationship with Him. Moses indicates that God's curses were precisely designed to teach the nation of Israel how to live a holy life.

So it shall be when all of these things have come upon you, the blessing and the curse which I have set before you, and you call them to mind in all nations where the Lord your God has banished you, and you return to the Lord your God and obey Him with all your heart and soul according to all that I command you today, you and your sons, then the Lord your God will restore you from captivity, and have compassion on you, and will gather you again from all the peoples where the Lord your God has scattered you. If your outcasts are at the ends of the earth, from there the Lord your God will gather you, and from there He will bring you back. The Lord your God will bring you into the land which your fathers possessed, and you shall possess it; and He will prosper you and multiply you more than your fathers. (Deut 30:1-5)

The New Testament, on the other hand, does not use the phrase "Day of the Lord" as a call to return to a covenant relationship; instead, it is a warning that Final Judgment is coming. For Believers, it meant be stay faithful and not be deceived by false teachers. For non-Believers, it was a call to place your faith in Jesus Christ for the God is "patient toward you, not wishing for any to perish but for all to come to repentance."