When I’ve taught preaching either in a course or a seminar, I’ve regularly encountered a certain question. “Why do you focus on preaching a single passage so much and not give instruction on preaching topically?” My response is hopefully balanced but instructive to those that ask.
There is a place for topical preaching, but not a steady diet of it. Sometimes a situation calls for a biblical message that encompasses several passages. But God gave us a collection of books, rather than topical studies, so we do well to usually feed on the Bible book-by-book. I remember at seminary that the president was working his way through Luke in the family chapel each Thursday morning. Then there was a mini-crisis on campus caused by some confusion regarding aspects of spiritual warfare. So for two Thursdays he addressed the issues in a biblical and clear manner using expository-topical messages. Then he returned to Luke for the rest of the semester.
Topical preaching is much more work. For many preachers a topical sermon is a short-cut. Instead of working in a specific text, they are free to speak on what they want using the verses they know to support their thought. This may be topical preaching, but it is not expository-topical preaching. Let’s say a message has three points, each with its own text. To truly preach that message the preacher has to do all the exegetical and homiletical work in each text, while constantly re-evaluating to make sure the overall message idea is fair to the texts. In simple terms, three passages mean three sets of study. To preach this way well is much more work.
Since it is harder, I don’t teach it on an introductory course. If I were to teach a series of three or four homiletics courses, with each a pre-requisite for the next, then topical preaching would be taught in the third or fourth course. Hence in a first preaching course I would rather have people understand the basics and do them well. It’s better to learn to ride a bike first, before introducing complicated ramp stunts.