Joel 1-3 Joel’s short book of prophecy is used by the NT writers on more than one occasion and recalling the words of Moses to God about His impending discipline. God was ready to “wipe them off the map.” But, Moses reminded God that if He did that, the nations around them would say: “Where is their God?” It would be an occasion to mock God, so God listened to Moses’ argument and relented.
On Pentecost, Peter used the prophecy of Joel about the Holy Spirit and His power. [Acts 2:18-32] Also, Paul used Joel as a call to salvation. “Call upon the Lord and be saved.” [Rom 10:13]
The book hinges on this one point: God’s character: “He is merciful and compassionate, slow to anger and boundless in loyal love—often relenting from calamitous punishment.” [Joel 2:13]