Preach against Unbelief
In order to transform people, preaching aims to increase their faith. The desired progression is from sin to holiness (sanctification), which requires faith. A person will only be changed through truly believing the Word of God. Whether Christian or not, all of us have the same problem: we do not believe the Word of God enough to let it shape our lives in every way. Therefore the preacher must target the unbelief in the hearer, and proclaim the Word as beacon that draws forth true faith from those in whom the Spirit works.