Who knows? He may turn and have pity and leave behind a blessing - grain offerings and drink offerings for the LORD your God. (Joel 2:14)
The prophet Joel is telling Judah here that perhaps with fasting and weeping they can touch the heart of God and He may leave a blessing on them even though they had committed great iniquities.
He addressed the nation:
'Even now,' declares the LORD, 'return to me with all your heart, with fasting and weeping and mourning.' Rend your heart and not your garments. Return to the LORD your God, for he is gracious and compassionate, slow to anger and abounding in love, and he relents from sending calamity. (Joel 2:12, 13)
The specific sin that is mentioned in this book is - Drunkenness. It suggests a self-indulgent lifestyle pursued by those who value material things more than spiritual.
Do we as believers also value material things more than spiritual? Are our prayers always focused on the material than the spiritual? I think we can assess ourselves. Measure the amount of things that we pray for as "Material" & "Spiritual" and put the percentage on paper. Most of us will be amazed. Material scores very high. God help us.
Here’s an exhortation from the Apostle Paul for all of us:
Be very careful, then, how you live - not as unwise but as wise, making the most of every opportunity, because the days are evil. Therefore do not be foolish, but understand what the Lord's will is. Do not get drunk on wine, which leads to debauchery. Instead, be filled with the Spirit. Speak to one another with psalms, hymns and spiritual songs. Sing and make music in your heart to the Lord, always giving thanks to God the Father for everything, in the name of our Lord Jesus Christ. (Ephesians 5:15-20)
For you were once darkness, but now you are light in the Lord. Live as children of light (for the fruit of the light consists in all goodness, righteousness and truth) and find out what pleases the Lord. Have nothing to do with the fruitless deeds of darkness, but rather expose them. (Ephesians 5:8-11)