The Last Judgment is the final time when God will judge everyone who has ever lived.
The Day of the Lord in the Old Testament
Many prophets in the Old Testament wrote about this time. They called it "the Day of the Lord." They said God would defeat all evil nations and set up his kingdom in Zion, his holy city (Isaiah 4:2; 11:10; Jeremiah 50:3–32; Joel 2:1–3; 3:9–16; Amos 5:18–20; 9:11; Zephaniah 1:7–18).
Jesus as the Judge in the New Testament
The writers of the New Testament also wrote about this judgment. They explained it through what Jesus taught and did. God has chosen Jesus to be the judge of everyone, both those who are alive and those who have died (Acts 10:42; 17:31). Everyone (both those who believe in Jesus and those who do not) will stand before Jesus's judgment seat. He will judge them based on how they lived their lives (2 Corinthians 5:10; compare Romans 14:10).
God's Standards for Judgment
God will judge people based on how they have lived. People who are faithful to God's covenant (agreement) with them will live, but those who turn away from God will die. The prophet Habakkuk says that a good person is someone who remains faithful to God (Habakkuk 2:4). The New Testament writers say that God will judge people by looking at whether their actions pleased him (2 Corinthians 5:10; Revelation 20:12).
But the New Testament also tells us that no one has fully met God's standards. Everyone has done wrong things ("all have sinned and fall short of the glory of God," Romans 3:9, 23). However, at the final judgment, the most important question is not whether someone has done wrong things. Instead, the question is whether God has forgiven them.
Believers and Unbelievers on the Day of Judgment
The New Testament (Romans 3:21–28; 5:1–21) describes this forgiveness as being made right with God (justification) and having a restored relationship with him (reconciliation). People can receive this forgiveness because Jesus died and came back to life. His perfect life and death make it possible for everyone to be forgiven and have eternal life (Romans 5:18).
People who trust in Jesus will not be condemned (John 3:16–18). They can enter the day of judgment without fear (1 John 4:17). Their names are written in a special book, called the Lamb's Book of Life (Revelation 21:27). But people who do not believe in Jesus will stand before him alone when they are judged. Jesus will judge them based on what they have done, which is recorded in his books (Revelation 20:11–12).