Joel
Introduction
The Biblical prophets knew that everything is temporary in our world. In every event threatening the lives of the people, they saw the coming of the Lord who judges this world to establish the final world.
Joel speaks when the land is invaded by locusts. The people are looking at their ruined fields and their lost crops. Joel looks beyond: The day of Yahweh is exceedingly great, terrible and dreadful—who can endure it?
Along with the promise of freedom from this plague, God also promises a happy age in which there will be neither grief nor fear. A day is announced when God will give the Spirit of the prophets to all his children: for the Church, Joel is the prophet who announced Pentecost, as Peter said on that day (see Acts 2:17).
2.12 Return to me with your whole heart: an invitation to penance. In times of hardship, public fasts were proclaimed in Israel. People would wear mourning clothes, or they would replace their clothes with sackcloth, or they would not comb their hair and cover their faces with ashes. In the Gospel, Jesus will not say that these signs of physical penance, like fasting to express sorrow and to accompany prayer, are useless (see Mt 4:1 and Mk 2:20), but will make it clear that these external signs of penance are not everything, nor are they what is most important.
3.1 Joel announces the Day of the Lord, a term indicating God’s coming Judgment, and the salvation of the elect, at the same time.
I will pour out my spirit on every mortal. Already, in the days of the Old Testament, God communicated his Spirit to the prophets and to saviors (see Is 11:1 and Jdg 11:1). Here, however, it is a decisive sign that the Spirit will be given to all believers. They will dream dreams and see visions. In those remote days, such were normal means of prophetic communication. Through these words, Joel announces what Isaiah did, when he said: All your children will be taught by God (Is 54:13 and Jer 31:31).
I will show wonders in the heavens (v. 3). The wave of prophesy will accompany many signs, indicating a grave crisis in the world. The image of the sun turning to darkness expresses both chaos in nature and impossible situations in the life of humankind.
Then all… will be saved (v. 5). This will be a time when people will not be able to avoid a decisive choice: to retain their former lifestyles or to invoke the name of the Lord, which means to surrender their lives and hopes to him, and rely on his powerful intervention.
It seems that these three factors were present for the Jewish people in the years following the resurrection of Jesus and before the destruction of the nation. Peter quotes this text on the day of Pentecost (Acts 2:17).
4.1 We can apply to this chapter what is said concerning Zechariah 12–14. The prophet uses a crisis, in which the Jews were harshly oppressed, to emphasize that God is the Lord of history.