1 Corinthians 1:18, 21, 23

The teaching about the cross is foolishness to those who are being lost, but to us who are being saved it is the power of God.

In the wisdom of God the world did not know God through its own wisdom. So God chose to use the message that sounds foolish to save those who believe.

But we preach a crucified Christ. This causes the Jews to stumble and is foolishness to non-Jews.