While topical sermons are based on human problems and issues, expository sermons are based on Biblical texts.

The Sermon on the Mount is a very good example of an expository sermon. In his sermon, part of which is as follows, Christ lays down all Christian codes of practice.

On adultery:

You have heard that it was said to those of old, “You shall not commit adultery”. But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart.

On committing sins:

If your right eye causes you to sin, pluck it out and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell. And if your right hand causes you to sin, cut it off and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell.

On hypocrisy:

How can you say to your brother, "Let me remove the speck from your eye'; and look, a plank is in your own eye? Hypocrite! First remove the plank from your own eye, and then you will see clearly to remove the speck from your brother's eye.

In the above example we can see that one chapter deals with three different issues.

In an expository sermon, the preacher flows through the text and keeps developing the author's thought simultaneously, just like how a college poetry teacher does. The meaning of poetry depends upon how the reader or listener perceives it. The same principle applies to expository sermons. Biblical texts may sometimes be misinterpreted, unless the preacher is careful when he writes the sermon.