Every sermon should have a text.  That is to say, it should be an explication and application of some portion of Holy Scripture.

A distinction is often made been ‘textual preaching’ and ‘expository preaching’.  The supposition is that there is a fundamental difference between preaching from a short section of the Bible (a single verse, say) and preaching from a longer portion (such as a paragraph).  But there is (or should not be) any fundamental difference.  Whether the text is a single sentence or an entire chapter, the sermon should be a true exposition, not using that sentence as an isolated motto, but rather placing it in its proper context.

There are two kinds of single propositions that may properly be taken as texts for sermons.  The first kind are the capital texts: those which sum up cardinal truths of the Bible (such as original sin, the divinity of Christ, the new birth, the Lord’s return) and from which the preacher may appeal to other parts of Holy Writ in order to fill out the meaning.  The second kind are the epitome texts, which contain the main point of an entire passage (as Rom 6:1 sums up the ensuing discussion, and Lk 18:7f gives the intended ‘moral’ of a parable).  In both cases, of course, the preacher must expound the entire passage, while paying special attention to the shorter section he has chosen as his text.

But the usual expository method should be that which explains and applies extended passages of Scripture.  No teacher of science, or geography, or any other subject, would proceed by extracting isolated fragments from a text book and presenting them out of context.  In the same way, the message of a book of the Bible is to be unfolded so that the hearers may grasp the overall flow of its story, message or argument.

Expository preaching shows how truth connects with truth.  Such preaching models to the hearers how to read the Bible for themselves.  It shows the symmetry of Bible truths, and promotes symmetry and stability of Christian character.

The pastor himself will profit immensely from a commitment to expository preaching.  The necessary study and discipline will shape both his ministry and his own character.  Moreover, it will relieve him of the tedious necessity of searching around for a text from which to preach, for his text is virtually chosen for him.  Subjects will crop up in the Bible passage to be expounded which would not lend themselves to whole discourses, but which can be handled more briefly, as and when they arise.  Then again, expository preaching enables the pastor to touch on sensitive subjects without any in his audience thinking that he is singling them out for particular personal rebuke.  He did not put the topic of predestination, say, or sexual faithfulness, into the Bible, God did.

Some fear that expository preaching will not interest the people.  But, nothing, really, can be of greater interest than to know the mind of God as he has revealed it in Scripture.  And the preacher himself should be find delight in it himself, and also render it as attractive as he can.  Expository preaching presents divine truth in those aspects and relations in which it was placed by God.  It is, accordingly, God’s chosen path to the human heart.  Nothing could be more important or pleasant that to follow that path and find hearts opened to God and his truth.

But is not the expository method too difficult, and too onerous?  Certainly, it is not easy.  But it will prove to be both the power and the wisdom of God unto salvation.

It might be supposed that an expository sermon lacks unity.  But this is to suppose that the Scriptures themselves lack unity.  In fact, the Bible readily divides into sections in each of which a leading theme may be identified and expounded.

Based on Dabney, Lectures on Sacred Rhetoric, chapter V.