“Let all who live in the land tremble, for the day of the Lord is coming. It is close at hand” (Joel 2:1) The New Testament calls it a day of “wrath,” a day of “visitation,” and the “great day of God Almighty” (Revelation 16:14) and refers to a still future fulfillment when God’s wrath is poured out on unbelieving Israel (Isaiah 22; Jeremiah 30:1-17; Joel 1-2; Amos 5; Zephaniah 1) and on the unbelieving world (Ezekiel 38–39; Zechariah 14). The Scriptures indicate that “the day of the Lord” will come quickly, like a thief in the night (Zephaniah 1:14-15; 2 Thessalonians 2:2), and therefore Christians must be watchful and ready for the coming of Christ at any moment. Read more "What is the day of the Lord?" http://www.gotquestions.org/day-of-the-Lord.html (Like/tweet)