As I instruct students in homiletics, one of the distinctions I try to help them see is that of preaching versus teaching. Clearly, pastors must do both, and there is a great deal of overlap. After the apostles were beaten by the Jewish authorities, they were released and we are told that they "did not cease teaching and preaching that the Christ is Jesus" (Acts 5:42). So they both taught and preached, yet the use of both of these words does denote a difference.
In his book Why Johnny Can’t Preach, David Gordon points out this distinction in his critique of modern, Western preaching. He notes that many ministers in this generation talk about subjects, but do not bring out from the text what amounts to a “convincing, compelling weight on the soul of the hearer.” Men lecture behind pulpits instead of proclaim, sounding more like they are reading a commentary than urging their listeners with heart-felt truth.
So how do you distinguish between the two? First, let's be clear on what are not true differences. The difference between teaching and preaching is not that one appeals to the head versus the other is for the heart. Nor is it simply a matter of talking versus shouting. It is not that one is complex and the other is simple. And again, the two are not mutually exclusive. All preaching has teaching within it and, when you sit under a good teacher, true teaching about Christ will invariably have preaching coming through at points. So what are some valuable distinctions to be made? Let me suggest at least six important ones.
Heralding versus instructing. Two primary words in the Greek New Testament describing the activity of preaching are high-powered, active words. One word, kerusso, denotes the activity of a king's messenger proclaiming news in a city. The other, euangelizomai, speaks of announcing the good news of Christ. In contrast, teaching (didasko) denotes the imparting of knowledge and instruction in wisdom.
Certain moral obligation versus possible moral duty. In preaching, the minister is calling the congregation hearing the message to faith and duty. As Lloyd-Jones states, preaching is not just a talk, lecture, or commentary on a text. Rather, it is declarative in nature and lays upon the hearers moral imperative. Teaching, on the other hand, can imply duty but does not necessarily do so. For example, a sermon on the Gospel of Mark would necessarily obligate the hearers to believe and follow Christ. But a lecture on the historical background of the Gospel of Mark would not be morally binding in the same way.
First or mostly second person in address versus third person. In teaching on a Bible passage, it is fine only to ask and answer the question, "What was the author by the power of the Spirit saying to his original audience in the text?" Yet in preaching, one must go further. He must both ask and proclaim the answer, "What am I by the power of the Spirit saying to this congregation from this text?" The former question is answered in the third person; the latter question demands the second person in expression or, perhaps some times, the first person. I tell students that, when preaching, they are not to be like a museum curator merely pointing out an interesting historic fact or two about the text. Rather, they must address directly the people before them with the text.
Urgency unrelenting versus urgency intermittent. The preacher should yearn for unbelievers listening to him to respond in saving faith and for believers to take definitive steps in holiness. He should be earnest and persistent as he does. You can hear this in the Westminster Larger Catechism's Question 159 regarding preaching, when it says that preaching is to be done "in demonstration of the Spirit, and of power; faithfully, making known the whole counsel of God; wisely, applying themselves to the necessities and capacities of the hearers; zealously, with fervent love to God and the souls of his people; sincerely, aiming at his glory, and their conversion, edification, and salvation." Certainly a teacher can show glimpses of urgency, but it is preaching where this quality is to be inherent as they seek to bring sinners to repentance and faith, and believers to deeper levels of sanctification and experience of God. Preaching, as Dabney put it, sends forth a virtuous energy from the soul of the preacher to his hearers. It is not necessary for even good Biblical teaching to do this.
One point versus many. Whereas a teacher can address may subjects and have multiple, equal points through the course of a lecture, the preacher is to be burdened with one primary point as he comes to the pulpit. In a good message, the whole of the sermon with all its parts serves to press one main topic on the hearts of the hearers. This focus should come from the preacher himself, as he has the weight of truth on his heart about a subject that he believes God's people must hear and obey. From "the big idea" to "the point" to "the burden," homileticians and the books they write are consistent on this matter of a singular focus.
Speaking for Christ versus speaking of Him. Perhaps the most daunting aspect of preaching is that the minister is speaking on behalf of the Lord. Paul makes that clear when he says this of preaching:
How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent?" (Romans 10:14-15
James Boice has pointed out that the word "of" in the question "And how are they to believe in him of whom they have never heard?" is not there in the original. Rather, it should read "And how are they to believe in him whom they have never heard?" Hear the difference? As men are sent out to preach, Christ through his Spirit is speaking through them.
As Paul said elsewhere, "We also thank God constantly for this, that when you received the word of God, which you heard from us, you accepted it not as the word of men but as what it really is, the word of God, which is at work in you believers" (1 Thes. 2:13). Teaching can tell wonderful things about Christ, and every Sunday school class should do so. Yet only duly ordained ministers in preaching can make the authoritative claim that they represent the Lord.
Surely any one of these distinctions could be pressed too far. Other ones could be made. Yet recognizing there are differences between preaching and teaching is helpful toward longing and praying for the Lord to raise up men mighty in the Scriptures.