NET
21 For since in the wisdom of God the world by its wisdom did not know God, God was pleased to save those who believe by the foolishness of preaching.
Darby
21 For since, in the wisdom of God, the world by wisdom has not known God, God has been pleased by the foolishness of the preaching to save those that believe.
KJV
21 For after that in the wisdom of God the world by wisdom knew not God, it pleased God by the foolishness of preaching to save them that believe.