The prophet warned of judgment and mocked human pride. All human systems (religious, economic, military, and social) will face God's examination and be found lacking on the Day of the Lord. This is the final day in history when God will judge the wicked once and for all (1 Corinthians 1:8; 1 Thessalonians 5:2; 2 Thessalonians 2:2; 2 Peter 3:10; Revelation 20:7–15).
Sometimes, prophets used the phrase the day of the Lord (or others like it, such as that day) to describe specific times when God judged wickedness throughout history (see Isaiah 13:6, 9; Ezekiel 13:5; 30:3; Obadiah 1:15). On the Day of the Lord, only God will be honored. All human wickedness and pride will be defeated. This glorious day of God's arrival will fill wicked and arrogant people with fear (Isaiah 2:10, 19, 21).