

6.53 Joel -- The Day of the Lord
This term appears five times in Joel (Joel 1:15, Joel 2:1, Joel 2:11, Joel 2:31, Joel 3:14) and in other prophets as well. It often refers to the decisive intervention of God in history. In the New Testament, it refers to Christ’s coming to consummate history (1 Thess 5:1-3).
Joel "does not voice the popular notion that the day will be one of judgment on the nations but deliverance and blessing for Israel. Instead...he describes the day as one of punishment for unfaithful Israel as well. Restoration and blessing will come only after judgment and repentance" (NIV Study Bible, p. 1338).
The plague of locusts was only a precursor and a warning. Joel held out more than a hope that the worst might be averted for the people of God. Once the nation repented, rain and fruitfulness would then return:
"Be not afraid, O land; be glad and rejoice.
surely the Lord has done great things" (Joel 2:21).
The Lord would even regard the locusts’ destruction as a debt to be repaid to Israel:
"I will repay you for the years the locusts have eaten" (Joel 2:25).
But for the foreign nations, the Day will be one of vengeance, as Joel describes in chapter 3.