“Once I have found it (the main expositional idea), I write it out in a complete sentence because it is crucial that the main idea of the passage be clear in my own mind. Subsequent development of the text hinges on it. This becomes the target I aim for in the exposition. It is also the primary message I want my people to retain after they hear the sermon. So it is crucial that the proposition be carefully thought through and clearly stated. Everything else in the sermon builds to support, elucidate, convict and confront the hearer with the main truth. This means every expository sermon is a unit with one main theme or topic, rather than a rambling through verse after verse.”
John MacArthur
Rediscovering Expository Preaching
Dallas: Word, 1992 pp219-220