Foolishness in the Bible has nothing to do with being dumb. Foolishness is all about moral character. A foolish person in the Bible is a person lacking good sense or judgment from a moral perspective. It is a person with a lack of moral character, corrupt, estranged from God, and constantly breaking God's Law.
From Psalm 10, we learned that the unbelieving, foolish heart says: "There is no God." Again, it does not mean that they don't believe in God's existence, but their lifestyles certainly don't show it. They are corrupt, practice abominable deeds, and there is no one who practices good. Our culture and some religions believe that mankind is inherently good. But the Bible tells us that we are not inherently good. We are capable of many good things, but deep down, we have a foolish heart. Many good deeds can be performed with the wrong motivation and with very self-serving purposes.
When God looks down from the heavens, he does not find among human beings, one person who is good - in the biblical sense, with moral character and integrity, a person who is in relationship with God and never violates his law. There is none to be found. We are all sinners. I am a sinner. What then? What is our plight if God cannot stand the presence of sin and sinners will not stand on the day of judgment? The only solution to this problem is salvation. Humanity needs a Savior. We need to be saved from our sin to be able to enjoy the blessings of God.
The psalmist exclaims: "Oh, that salvation for Israel would come out of Zion!" And it has! The salvation plan is this: that God himself would come into the world to pay the penalty for our sin. The innocent dies for the guilty to fulfill all justice and be able to offer heaven, eternal life, as the reward for all those who trust in that salvation. We must trust in our Savior. Our Lord Jesus Christ. It is the only way to be saved from my foolishness, corruption.
Father, thank you for the salvation plan. Thanks for sending your Son Jesus Christ into the world to save us. Help me trust in him every day of my life that I may not be consumed by my foolishness. May I convey your salvation plan unto others. Amen.