Definition and Overview:
Judgment Day, often referred to as the "Day of the Lord" or the "Last Judgment," is a future event in Christian eschatology when God will judge the living and the dead. This day is characterized by the final assessment of humanity by Jesus Christ, determining the eternal destiny of every soul. It is a central theme in Christian doctrine, emphasizing accountability, divine justice, and the fulfillment of God's redemptive plan.

Biblical References:
The concept of Judgment Day is extensively covered in both the Old and New Testaments. In the Old Testament, the prophets frequently spoke of a coming day of reckoning. For instance, the prophet Joel declares, "The sun and moon will grow dark, and the stars will no longer shine. The LORD will roar from Zion and raise His voice from Jerusalem; heaven and earth will tremble. But the LORD will be a refuge for His people, a stronghold for the people of Israel" (Joel 3:15-16).

In the New Testament, Jesus Himself speaks of Judgment Day in the Gospels. In Matthew 25:31-46, He describes the separation of the righteous from the wicked, likening it to a shepherd dividing sheep from goats. Jesus states, "When the Son of Man comes in His glory, and all the angels with Him, He will sit on His glorious throne. All the nations will be gathered before Him, and He will separate the people one from another as a shepherd separates the sheep from the goats" (Matthew 25:31-32).

The Apostle Paul also addresses this event, emphasizing the inevitability of divine judgment. In Romans 14:10-12, he writes, "For we will all stand before God’s judgment seat. It is written: 'As surely as I live, says the Lord, every knee will bow before Me; every tongue will confess to God.' So then, each of us will give an account of himself to God" .

The Book of Revelation provides a vivid depiction of Judgment Day, portraying it as the culmination of history. Revelation 20:11-15 describes the great white throne judgment, where the dead are judged according to their deeds. "Then I saw a great white throne and the One seated on it. Earth and heaven fled from His presence, and no place was found for them. And I saw the dead, great and small, standing before the throne, and there were open books. And one of them was the book of life. The dead were judged according to their deeds, as recorded in the books" (Revelation 20:11-12).

Theological Significance:
Judgment Day underscores the holiness and justice of God, affirming that He will ultimately rectify all wrongs and reward righteousness. It serves as a reminder of the moral order established by God and the accountability of every individual. The anticipation of this day encourages believers to live in accordance with God's will, fostering a life of faith, repentance, and obedience.

Eschatological Context:
In Christian eschatology, Judgment Day is closely associated with the Second Coming of Christ. It is believed to occur after the resurrection of the dead and the final defeat of evil. The righteous, whose names are found in the Book of Life, will inherit eternal life, while the wicked will face eternal separation from God.

Practical Implications:
For Christians, the doctrine of Judgment Day serves as both a warning and a source of hope. It calls for a life of vigilance, spiritual readiness, and moral integrity. The assurance of God's ultimate justice provides comfort to believers, affirming that their faithfulness will be rewarded and that evil will not prevail.