Whether you’re an experienced or novice preacher, we would all be wise to take this advice from Mark Dever and Greg Gilbert to heart:
Your sermons should never be forty-five-minute morality lessons or best practices for living a better life. They should drive forward to the good news that King Jesus saves sinners through His life, death, and resurrection from the grave. In fact, we think that in every sermon you preach, you should include at some point a clear and concise presentation of the gospel. Tell people how they may be saved! I never want someone to come to my church, not just for a length of time but even for one single service, and be able to say they didn’t hear the gospel of Jesus Christ. Brothers, you are not Jewish rabbis. You are not called to give sermons that merely tell people how to live rightly or better. Is teaching people to live rightly part of preaching the whole counsel of God? Yes, absolutely, depending on the text! Is that ever all there is to it? Absolutely not! One way or another, every text in the Bible points to Jesus, and you should follow where it points. . . . It’s easy to preach the Bible, especially the Old Testament, as if it were a book of fables—a series of stories that do little more than instruct us morally. But if we believe Jesus, we know those stories are doing much more than that; they are pointing us to Him. So whether we do it by following the story line or pointing out the themes, our job is to show our congregations how to see Jesus, even from the story of Ehud.
Mark Dever and Greg Gilbert, Preach: Theology Meets Practice (Kindle locations 1525, 1560)