I Corinthians 2:1-5

And I, brethren, when I came to you, did not come with excellence of speech or of wisdom declaring to you the testimony of God. For I determined not to know anything among you except Jesus Christ and Him crucified. I was with you in weakness, in fear, and in much trembling. And my speech and my preaching were not with persuasive words of human wisdom, but in demonstration of the Spirit and of power, that your faith should not be in the wisdom of men but in the power of God.