Preachers are to preach God's Word, and God's Word alone. They are NOT to preach human wisdom or human opinion!
People can be persuaded with human wisdom and opinion, but they remain unchanged spiritually. However, if the preacher preaches God's Word alone, in the power of the Holy Spirit, God uses His Word to change peoples hearts for glory!
Indeed our faith is not in the wisdom of men, but rather in the power of God as Christ and Him Crucified is preached faithfully!