12 “Now, therefore,” says the Lord, “Turn to Me with all your heart, with fasting, with weeping, and with mourning.” 13 So rend your heart, and not your garments; Return to the Lord your God, for He is gracious and merciful, slow to anger, and of great kindness; And He relents from doing harm. 14 Who knows if He will turn and relent, and leave a blessing behind Him— A grain offering and a drink offering for the Lord your God? (Joel 2:12–14, NKJV)
The southern kingdom of Judah faced the “great and very terrible” “day of the Lord” – God’s approaching judgment against her sins in the form of an invading army of locust (Joel 2:11; 1:4-7; 2:1-11). Joel’s prediction of imminent judgment is followed by this call to repent and return to God. The prospect of judgment is a reason to repent and turn back to God (Acts 17:30-31). It is not easy to repent. One must turn the heart totally back to God. To accomplish this, the heart must be crushed by the weight and gravity of its own sin: “fasting…weeping…mourning” indicates the contrite heart that is ready to change and fully turn to God. Only with a contrite heart can we “return to the Lord your God” and expect His gracious mercy to replace judgment with blessing.