Joel 2 begins with a dire warning that I believe is relevant today. I believe that God's judgment on the whole earth is very near and that disasters and distress we are experiencing are just the beginning of birth pains.
The Day of the Lord is at hand.
Joel 2 begins with a warning that the Day of the Lord is very near. The people are warned to blow the trumpet and sound an alarm. The watchers are to warn the people of danger (Ezekiel 33). Joel 1:3-11 give a vivid description of this army. Vs 10-11 speak of the darkening of the sun and reddening of the moon as signs coinciding. This places this battle in the end-times.
Call to Solemn Assembly
In vss 12-17, there is a call to repentance- specifically a call to what the Bible refers to as a Solemn assembly. While solemn assemblies were instituted under the Mosaic law, the application of it's key component, the solemn assembly, transcends the limitations of the Mosaic law. The solemn assembly was critical to the Feast of Tabernacles. Seven days of observance is followed by a solemn assembly on the eighth day (Lev 23:36).
When the temple of Solomon was dedicated (2 Chr 5-7) it was at the time of then Feast of Tabernacles. They observed seven days and had a solemn assembly on the eighth day. During that solemn assembly, fire came down from God and the priests fell under the power of God. (2 Chr 7:1-9)
We know from the passion narratives that on the third day after Christ died, He rose from the dead. He ascended into heaven 40 days later. the apostles were commanded to abide in an upper room. The apostles stay in the Upper Room where they engaged in “prayer and supplication”; this was engagement in a solemn assembly.
In Zech 14:16-21, which speaks of the time after the Day of the Lord judgment, that the Feast of tabernacles was both a regular and international Feast day.
The call to solemn assembly or sacred assembly is applicable to all legal contexts, not just the Mosaic Covenant. The call to seek God in solemn assembly for public and collective repentance is for today. We are to make prayers and supplication for redemption and revival in the context of impending doom for God to glorify himself by reviving us.
Vss 18-27 promise physical restoration, including deliverance from our adversaries. In context the adversary is the Gog coalition that surrounds Israel and breathes out murders against God's people ( Ezekiel 38-39).
Spiritual Restoration – End Time Revival.
The other promise is that of great revival. Vss 28-32 are also recorded in Acts 2 as the prophetic basis of Pentecost. In the context of Joel, this revival occurs before the End-time Day of the Lord judgments. That is why Joel's prophecy includes the darkening of the sun and reddening of the moon as signs accompanying the revival. The revival in Acts was the initial, but not complete, fulfillment of Joel's prophecy. The complete fulfillment occurs just before the Return of Jesus Christ.
The initial awakening resulted in a mighty movement of the Holy Spirit. The end-time revival will see both a continuation of the this mighty move and great manifestation of the Sovereignty of God: The sun darkening and the moon reddening followed by judgment on the nations and great deliverance of His people.