The day of the Lord is the moment when God appears to intervene and judge sinners (Isaiah 13:6, Isaiah 13:9; Ezekiel 13:5; Ezekiel 30:3; Joel 1:15; Joel 2:1, Joel 2:11; Joel 3:14; Amos 5:18, Amos 5:20; Zephaniah 1:7, Zephaniah 1:14; Zechariah 14:1; Malachi 4:5; Acts 2:20; 1 Corinthians 5:5; 1 Thessalonians 5:2; 2 Thessalonians 2:2). For those who belong to him, it will be a day of salvation (Joel 2:21–32; Joel 3:18; Obadiah 1:15–21; Zechariah 14:1–21).1 The New Testament affirms that the day of the Lord is the day of Christ’s return (1 Corinthians 1:8; 2 Corinthians 1:14; Philippians 1:6, Philippians 1:10; Philippians 2:16).2
10 But the day of the Lord will come like a thief, and then the heavens will pass away with a roar, and the heavenly bodies will be burned up and dissolved, and the earth and the works that are done on it will be exposed.