I’ll give you my answer in a minute, but first, here are a few answers I often hear that I don’t think stack up.

1. Preaching is fiery and shouty, whereas teaching is meticulous and dry. I’ve yet to meet a leader who defends this one, thank goodness, but it’s amazing how many people in your life group would come up with something like it.

2. Teaching is based on the Bible, whereas preaching is more prophetic or personal. Worryingly, I have heard this one defended. All I can say is that if our preaching is not based on the Bible, we have bigger problems than working out how to tell the difference between preaching and teaching.

3. Preaching aims at the heart, and teaching at the head. There’s a grain of truth in this one – preachers are, of course, trying to reach the heart – but only a grain. After all, if preaching does not aim at the mind and the will and the emotions, an awful lot of people are simply not going to be affected by it. My guess is that this statement, when it appears, emerges from traditions that are pietist/revivalist as opposed to confessionalist.

4. Preaching is topical, whereas teaching is systematic. Needless to say, there is no such distinction made in Scripture.

5. Preaching has to be simple, whereas teaching is often more complex. Well, it depends who you’re talking to, doesn’t it? If you’re teaching people with a very low level of biblical literacy, then you need to be extremely simple; if you’re preaching to people with a very high level of biblical literacy, it might well be more complex. Jesus’s teaching to Galilean peasants seems to have been pretty simple.

6. Teaching aims at information, whereas preaching aims at revelation. Bunk. Superspiritual, Gnostic bunk.

So I don’t think it’s any of those. In fact, I think the answer is more straightforward than any of them, and rests in the meanings of the words themselves. A kerux (the usual word for “preacher” in the New Testament) in the ancient world was simply a herald: a guy who rode into town to deliver significant news. A didaskalos (the usual word for “teacher”) was an instructor: someone who explained or taught something to someone else. There, it seems to me, is the difference. Preaching is proclaiming, heralding and announcing news to people – the gospel – especially (but not exclusively) to those who haven’t heard it before. Teaching is explaining things about the gospel that people don’t understand, and instructing them on how to live in light of it.

The most helpful illustration of this comes from John Piper. He pictures a herald riding into town, shouting from high atop his horse, “Hear ye! Hear ye! The Emperor has declared an amnesty to all slaves!” That, Piper says, is preaching: proclaiming good news, announcing something that has happened, that completely changes the situation of the listeners. But he then imagines people approaching the herald with questions. What does amnesty mean? When does this announcement take effect? Does that mean I can leave my slavemaster now? Will compensation be paid to masters? And so on. At that point, Piper says, you have to start teaching: explaining the implications of the news, helping people with concepts and ideas they don’t understand, and telling people what they need to do in response, given their various situations.

In other words, the difference between preaching and teaching is not shouting versus whispering, or illuminating versus bamboozling, or revealing versus informing. In a nutshell, it’s the difference between heralding and explaining. (That may mean that an awful lot of our Sunday “preaching slots” don’t contain any “preaching” at all, of course – but that’s another story.)