In Joel 2:12, the Lord declares, “return to me with all your heart, with fasting, with weeping, and with mourning.” This call to repentance is given in the context of the swarming, hopping, and cutting locusts (i.e. the great army of the Lord, see 2:25) sent according to the judgment of the Lord and the day of the Lord, referring to the coming of the “northerner” who will execute his word (see 2:11).
Why are they called to repent with weeping, fasting and mourning? Previously, Drew made the point that there are three essential aspects of biblical repentance: 1) intellectual, 2) emotional, and 3) volitional. In v. 12, weeping, fasting and mourning are seen as the visible signs of repentance (cf. Joel 1:5-14). It is important to see this call to repentance in view of the beginning of v. 13, “and rend your hearts and not your garments.” In view of that, the kind of repentance necessary is one that affirms God’s righteousness and our lawlessness, including one that also affirms lordship and confesses our sinful rebellion.
If they are willing to weep, then they are willing to show they realize their sin against God, and that their only hope for salvation is in his hands. Their sin was an offense against God. Therefore, they should weep knowing they had openly sinned against the God who came down to them and made covenant with them. They should fast to show their desire for the Lord is even greater than their hunger. They should mourn because they realize they deserve judgment from the Lord and they are helpless to save themselves (cf. 2 Cor. 7:8-11).
Finally, Joel’s call to repentance reminds Israel that having a covenant relationship with God is special. They cannot maintain their relationship with the Lord on their own terms and they cannot follow the Lord with just their routine (e.g. instead, “rend your hearts and not your garments”). They must follow him with their hearts. It seems that the people were more legalistic about their worship of God than genuine. The people felt that they could please the Lord by following rules, but their hearts were far from him. If their hearts were far from the Lord, then they were doing nothing more than pleasing their own hearts. In view of this false devotion, Joel dramatically announces the coming judgment of the Lord: “Blow a trumpet in Zion; sound an alarm on my holy mountain! Let all the inhabitants of the land tremble, for the day of the Lord is coming; it is near” (2:1).
But there is hope. If they truly repent, Joel writes, “[the Lord] is gracious and merciful, slow to anger, and abounding in steadfast love; and he relents over disaster” (v. 13).
“And it shall come to pass that everyone who calls on the name of the Lord shall be saved. For in Mount Zion and in Jerusalem there shall be those who escape, as the Lord has said, and among the survivors shall be those whom the Lord calls” (v. 32).
This is also clearly seen in Jer. 32:36-44. The call to the survivors will also include a call to repentance similar to 2:12-13: “Return to me with all your heart, with fasting, with weeping, and with mourning; and rend your hearts and not your garments.”