1 Corinthians 1:25 (NIV)
25 For the foolishness of God is wiser than man's wisdom, and the weakness of God is stronger than man's strength.
This world will try to tell you that "people are essentially good, that if we just believe in ourselves, we can accomplish anything. We don't need God, and we don't need a Saviour. We can be our own saviour. All we need is ourselves." That's man's wisdom, the wisdom of this world. This "wisdom" is what the Corinthians were hearing incessantly from the mouths of so-called wise men, teachers of the law and "philosophers of this age" (v20).
Today you hear this same "wisdom" trumpeted by celebrities, artists, university professors, key note speakers at graduation ceremonies, and teachers of every religion (except Christianity). "Believe in yourself and you'll be fine" has always been the world's wisdom, and it shows up in all sorts of different forms. The religious version of this wisdom is, "If you try hard enough, you can get yourself into heaven and become your own god." The non-religious version is, "Believe in yourself, be whatever you want to be, do whatever you want to do, as long as you're happy. You don't need God." Either way, the world's wisdom is about pridefully putting your faith in yourself.
In contrast, the message of Christianity is the complete opposite. Yes, we may be capable of doing some good, but we're not nearly as good as we think we are. We are sinners in need of God's grace, forgiveness and most importantly, a Saviour. That's why God sent His Son Jesus Christ: to be the Saviour that we so desperately need. Jesus died on the cross for sinners like us. And when we humble ourselves and admit our need for that Saviour, that is our salvation.
Because the message of Christianity is so different, so radical, so counterintuitive compared to the world's wisdom, many people either misunderstand it or reject it. As Paul says in verse 18, "the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God." It's a "stumbling block" for those who rely on this worldly "believe in yourself" wisdom (see v22-24).
By sending Jesus Christ to save us, God was rejecting all the human wisdom that says "believe in yourself". As verse 19 says, "I will destroy the wisdom of the wise; the intelligence of the intelligent I will frustrate".
For the world, belief in Christ is foolishness, yet God uses what the world calls foolish to save us. That way no one can say "I did it myself"; everyone can only say, "It's only because of God's grace".
When I think of it this way, verses 21 through 31 make so much more sense:
"For since in the wisdom of God the world through its wisdom did not know him, God was pleased through the foolishness of what was preached to save those who believe." (v21)
Jesus, thank You for becoming a fool for us, how you allowed yourself to be accused, abused, punished and tortured like the worst of criminals, and you took it all without protesting. You were the Son of God, yet You allowed Yourself to become "weak", even submitting to death on a cross at the hands of people. Thank You that it is Your "foolishness" and Your "weakness" that have saved us, something which man's own highest wisdom and greatest strength could never come close to doing. Thank You for Your foolishness!