I believe that the failure to make a distinction between preaching and teaching is one of the key reasons for poor sermons. Sermons that are more teaching in content and style of presentation but attempt to pass off as preaching is a serious cause of disconnect between the preacher and the people in the congregation. The what and the why of preaching and teaching are different, and hence, when a speaker employs them depends on whether he is preaching or teaching.
To understand the difference between the two we must first look at their respective purpose. The purpose of teaching is to help people understand the Bible and it’s truths; to help the listeners know about God and what He has said. Broadly speaking, teaching addresses the mind more than the heart. This does not mean that the teacher does not challenge his students to apply the Word into their lives. He does, and he must, as teaching of the Bible has to lead to life-change.
On the other hand, the purpose of preaching is to help people hear what the Word of God is saying to them now. It targets the heart; to inspire, challenge and cause the listeners to apply God’s Word in their lives—leading to life-change.
The sermon at a worship service is where preaching ought to take place. However, in many churches (across all denominations, but especially among conservative evangelical churches) teaching makes up the bulk of the sermon. Explanation is given by the preacher about how he had arrived at his interpretation. He may go into the original language, provide the historical context of the Bible text, take the listeners on a tour of the geography, give the different possible interpretations as he quotes this and that scholar, and refers to other Bible references to underscore his interpretation, but he never gets to the address the question, So what?
What? is what teaching focuses on. So what? is what preaching should focus on. It is the message of the passage; the big point of the sermon. It cannot be left to the last five minutes of the sermon; the preacher would have lost his listeners to the message because he had lost them with his elaborate explanation of the text. The message may be hinted at early in the sermon; certainly it must be developed as the sermon is preached, with plenty of time for amplification and application after the thrust has been stated. For a sermon to have been effective, the listeners must go away knowing clearly what the message was about and be impacted by it.
Is teaching not important in a sermon? It certainly is—very important, because the message is based on the Bible. In other words, teaching must be the basis of the preaching; teaching must inform the preaching. However, in a sermon the teaching content cannot take a disproportionate amount of time. The preacher does not do his exegesis at the pulpit; he does that in his study. At the pulpit he preaches the message that he has distilled from his study, having sought the Lord in prayer, and under the inspiration of the Holy Spirit.
The pulpit at the weekly worship service is not the place to do teaching (I should qualify that with the word “elaborate”). Bible classes and special seminars are the places where more in-depth Bible teaching happens. And that, we must have in our churches. Christians must be know the Word of God; they must be taught the Bible. But not through the sermon at the weekly worship service (don’t take this sentence out of context!). The purpose of preaching is to bring a message from the Lord based on the Word of God to the listeners that they need to hear now.