Why do people consider God foolish for saying He can save anyone?
People consider God foolish because they judge by human wisdom. In man's eyes, it seems impossible and foolish that God can save a person from the most utter, gutter-type existence and make him a saint. Such a transformation offends mankind's wisdom, yet Scripture presents it as God's power and wisdom.
Les explains that the foolishness of God is foolishness in man's eyes, not in reality. Man thinks God is foolish when He says He can save a person from the most utter, gutter-type existence and make him a saint. That is foolishness to mankind. Paul's point in 1 Corinthians is that preaching Christ crucified is the basis, and to the called—Jew or Greek—Christ is the power of God and the wisdom of God. God's wisdom is set apart from the wisdom of men; earthly wisdom does not make us something God can use. Les also notes we never know what God will use, even something we would never dream of, as with the old man who asked for the plan of salvation.
Because the foolishness of God is wiser than men; and the weakness of God is stronger than men.