Joel’s major theme is the “Day of the Lord” and the need for God’s people to be prepared. The “Day of the Lord” is used in Scripture to refer to different periods when God sent judgment to His people. The only way to avoid or reverse God’s judgment is to repent and believe in the Lord’s goodness and mercy. To call on his name!
Joel sees the “Day of the Lord” in three contexts. The Historical Day of the Lord – where he sees the plague of locusts as a judgement against Israel’s behaviour and attitudes. There is also a Gospel Day of the Lord when Jesus comes and receives God’s judgement for our sin, but He also gives His Spirit to all Christians to continue His mission to save people.
Then there is the End Times Day of the Lord where Jesus will return to wind up history and people will be judged according to their faith in Him.
Joel 2:32a “And everyone who calls on the name of the Lord will be saved;”.