Preach love, as well as truth
Whatever captures the heart’s trust and love also controls the feelings and behavior. What the heart most wants, the mind finds reasonable, the emotions find valuable, and the will finds doable. It is all-important, then, that preaching move the heart to stop trusting and loving other things more than God. What makes people into what they are is the order of their loves – what they love most, more, less, and least. That is more fundamental to who you are than even the beliefs to which you mentally subscribe. Your loves show what you actually believe in, not what you say or do. People, therefore, change not by merely changing their thinking but by changing what they love most. Such a shift requires nothing less than changing your thinking, but it entails much more.
So, the goal of the sermon cannot be merely to make the truth clear and understandable to the mind, but must also be able to make it gripping and real to the heart. Change happens not just by giving the mind new arguments, but also by feeding the imagination new beauties.
Tim Keller: Preaching: Communicating Faith in an Age of Skepticism, pp.159-160.