Joel 2:12-13, "Therefore also now, saith the LORD, turn ye even to me with all your heart, and with fasting, and with weeping, and with mourning: And rend your heart, and not your garments, and turn unto the LORD your God: for he is gracious and merciful, slow to anger, and of great kindness, and repenteth him of the evil."

Joel was a prophet of Judah during the reign of Joash. Because Judah began to turn away from the ways of the Lord, God sent His prophets to testify against them but they refused to listen.

Much of the prophesy sounds apocalyptical, moving from the present to the future, speaking of pestilence, famine, draught, and war. But one thing this 'trumpet of God' resounds loud and clear, his cry to turn and repent. 

II Peter 3:9-10, "The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance. But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up."

The book of Joel gives vivid insights into the the Day of the Lord. A day when all nations will be gathered to the battle of Armageddon, 'the valley of Jehoshaphat.' A day when God will judge the people of the earth, but the LORD will be the hope of his people, and the strength of the children of Israel.

The book of Joel reveals that today is the day the trumpet is sounding a call to repent and return to God before that great and terrible day, the Day of the Lord. Through the words of this prophesy we see God is a Jealous God, Qanna, Who watches over and corrects all those He loves.