There are a lot of things to think about when preparing a message. But how many of us think about how we think? And let me go one step further–how many of us think about the way we are leading our listeners to think?
For example, should I begin my message by telling them what my big idea is and then proceed to lead their thinking out of that idea through further development. Or, should I begin my message by getting them to think toward the (yet unstated) big idea and then proceed to lead them into it by the time I reach my conclusion.
In other words, what is the shape or movement of my sermon with reference to my big idea (or proposition or homiletical idea)? And how do I want my audience to think about it?
Of course, what happens at the macro level in considering the shape of the entire sermon also takes place at the micro level in considering the shape of individual sections within the sermon.
For example, how am I going to get my listeners to think about my first main idea or point in the message? Should I move toward the idea? Away from the idea? Into and then back out of the idea? Should I circle around or perhaps work through the idea?
Or, if I’m honest, do I really have no idea? That, unfortunately, is the way some sermons come across. “What is his point?” the listener thinks to himself or herself. Or, perhaps more commonly, “I have no clue how that illustration or that cross reference or that bit of  historical background had anything to do with the point he stated earlier.”
That’s why we need to wrestle with the question of shape. We need to know at each moment where we are in relationship to our main idea(s). We need to consciously and deliberately employ shapes that communicate those ideas most clearly and effectively.
Four Basic Shapes
Here is one way to visualize the various shapes available to us. In his book Using Rhetoric John Jordan enumerates four basic shapes, patterns, or forms of developing the topic sentence within a paragraph. For our purposes (since we’re not writing a paper), think of the topic sentence as your exegetical idea, or homiletical idea, or main point. You can even think of it more broadly as any idea you want to get across in a message. And think of the paragraph as any unit of thought within the sermon (like the introduction or a main point) or the sermon as a whole.
1. The Triangle Shape
The topic sentence standing first makes the simplest and most reliable kind of paragraph organization. We naturally declare what we are going to say and then say it, thus forewarning and preparing our readers. Furthermore, this paragraph structure reflects the wide-spread method of thought, . . . operating in deductive logic, of moving from generalization to particulars. A generalization is made at the beginning of the paragraph, and everything in the paragraph derives from and supports that generalization. If everything cannot be derived from the topic sentence, then something is wrong with either the topic sentence or the paragraph. (123, emphasis mine)
2. The Wedge Shape
One can construct a paragraph on the inductive pattern by pouring in details and concluding with a generalization contained in a topic sentence. The writer then gives the illusion of actually working out what he wants to say in the course of the paragraph, before the reader’s eyes. Perhaps in his rough draft the writer actually is uncertain of what he wants to say. But by the final version this working out of the material must be just an illusion designed to encourage the reader to think with the writer. (123)
3. The Diamond Shape
[It is a paragraph] beginning with a topic sentence and ending with a similar sentence which repeats the idea in different terms and perhaps leads to the next paragraph. This type of paragraph expands from a generalization and then narrows back into one. Thus it benefits by using both modes of thought [deductive and inductive] , expanding and then narrowing, and leaves an impression of having nailed down the point. (124)
4. The Hourglass Shape
The topic sentence [is] in the middle of the paragraph, so that some of the details add up to the generalization and some derive from it. (124)
There you have it–the four basic forms or shapes for developing your ideas: triangle, wedge, diamond, and hourglass. They look great on paper, don’t they? In real life, however, things are not always so neat and tidy. There can be many combinations of these basic shapes in an actual sermon leading to more complicated and complex structures. That’s okay.
The question we should be asking ourselves is not primarily, “Am I using one of the four basic shapes above, and can I identify which one?”
No. The questions we should be asking are these:
- Is there a deliberate and purposeful shape to my sermon overall and to the individual sections within?
- Am I employing the best shape to communicate the idea of the text, to accomplish the purpose of the text, and to impact the listeners for Christ.
So, what kind of shape is our sermon in? We need to think about the answer to this question. In fact, we need to think hard about the answer to this question. The unity and clarity and effectiveness of our sermon, from a human standpoint, is at stake.
If you’d like to read more along these lines, I would recommend Dennis Cahill’s book The Shape of Preaching.