Like prose and poetry, these two terms are better understood as opposite ends of a spectrum, rather than raw opposites. When we write prose we are given to sundry poetic devices, word-plays, metaphors, etc. and when we write poetry we are communicating information. In like manner it is rather difficult if not impossible to teach without preaching to some degree, or to preach without some level of teaching.
One way to illustrate the distinction however is to note the difference between the indicative and the imperative. The former tells us what is, the latter tells us what we’re supposed to do. Teaching, obviously, tends toward the indicative while preaching tends toward the imperative. But what if we made the distinction absolute? Would not any teaching utterly bereft of any imperative cause us to yawn, to reply, “So what?” In like manner, were we to drain preaching of all indicative, and be left with only imperative, would we not have sermons that merely shout, “Do something!”? Would it not end up sound and fury, signifying nothing?
Which means, in the end, that these are each matters of degree. I’ve been blessed to be able to teach at several colleges and universities. Because my desire for my students is that they would grow in grace and wisdom it is not my design to merely download information from my brain to theirs. My classes therefore tend to follow a real, though unplanned pattern. It usually happens that I spend roughly two thirds of my class time giving and explaining information. Then, in the final third of class I tend to commence to preaching. I begin to exhort my students to live in light of what they have learned, to change their perspectives, and their lives. I begin to implore them to change their hearts.
I have been blessed also to preach. Here I certainly have an obligation, as best as I am able, to explain the text. I seek to place the text in its historical context. I try to clear up any grammatical ambiguities, or translation issues. But, persuaded that the Bible is not some odd and mysterious book that isn’t eminently understandable, believing that our problems are more moral than intellectual, that we are more foolish than stupid, I exhort the congregation to believe, to trust, to rejoice, to give thanks, to love, to forgive. Every Sunday when I preach I walk into the pulpit not only hoping to be true to the text, but hoping to encourage growth in godliness. I want the flock to go away persuaded that in Christ they are beloved of the Father, and that Jesus changes everything.
We who are Reformed tend to be stronger teachers than preachers. The non-Reformed tend to be stronger preachers than teachers. We agree with the Bible, but remain unmoved by it. They are quick to be moved, but not always by the Bible. The Bible is not just filled with truth. It is filled with truth that ought to change us. It isn’t enough that we are taught the Bible. We need the Bible preached.