1 Corinthians 1:21; 1 Corinthians 2:4; 1 Corinthians 15:14

1 Corinthians 1:21

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.

1 Corinthians 2:4

4 And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power:

1 Corinthians 15:14

14 And if Christ be not risen, then is our preaching vain, and your faith is also vain.