The ideal sermon conclusion speaks to the mind by pulling together and briefly summarizing what the sermon teaches. But that is never enough. It also speaks to the will by encouraging the listener to act on what the sermon teaches.
Call to action
Peter's sermon at Pentecost was one of the most successful sermons of all time. Its climax models well the ideal call to action: "Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, 'Brethren, what shall we do?' And Peter said to them, 'Repent, and be baptized' " (Acts 2:37, 38, RSV).
A sermon should do more than dish out pleasant platitudes or helpful information. It should "cut to the heart" and leave listeners asking, "What shall we do?"
You've been in a home when there was a knock at the door. A voice from the kitchen announces, "There's somebody at the door." But the story doesn't end there. Things can never get back to normal until someone gets up and answers the door. A knock is not meant just to be announced. It is meant to be answered.
By means of their sermons, preachers intend to help listeners hear Jesus knocking at their doors. But proving He's there, available, is no way to end a sermon. A knock is not meant just to be announced. It is meant to be answered. It demands action. Every sermon should include a logical, nonmanipulative call to action.
That doesn't mean everybody's going to like the call. People seated comfort ably in the living room may not appreciate having to answer a knock at the door. Ezekiel reminds us that there are always persons willing to hear but unwilling to do: "And, lo, thou art unto them as a very lovely song of one that hath a pleas ant voice, and can play well on an instrument: for they hear thy words, but they do them not" (Eze. 33:32).
Semanticist S. I. Hayakawa explained that just as cats and dogs like to be stroked, people sometimes like to be stroked with words. More people are willing to hear preaching than are willing to be changed by it. Inactive folk instinctively dislike anything that calls for action. Call for it anyway. Love them enough that though you want to please them, you want even more to help them.
So the call for action requires thoughtful preparation. I notice that often when I hand my ticket to the agent at an airline ticket counter, I'm asked "And what is your final destination today?" It just doesn't make sense to set out on a journey without knowing where you're going. Lay your sermon before the Lord as you're preparing it and again before you preach it. Listen as the Holy Spirit whispers, "And what is your final destination to day?" Never set out on the journey until you know where you're going—what action you want your listeners to take.
Internal action
Peter's first call to action required an internal response—"Repent." It's a very specific and most significant response, yet it can be a very private and personal one. Your call to action need not be highly emotional, nor must the action to which you call your congregation be an immediately visible one. You don't have to do all the thinking for your listeners. Your call to action can come in the form of a question asked, options suggested, or a challenge offered.
The ideal call to action invites the listeners to experience here and now what the sermon has just taught. You don't preach on forgiveness so that people will believe that they can be forgiven, but so that by believing, they will experience forgiveness—now.
External action
Peter's second call to action required external action—"Be baptized." A sermon does not have to move its hearers to immediate external action to be effective, but expression does deepen impression.
Two men discuss a business deal. They shake hands as a physical expression of their agreement. A couple stand at the wedding altar. They exchange words and a kiss as an expression of their commitment. Expression deepens impression.
Invite your listener to be baptized, participate in Communion, fill out a card, come forward, raise a hand, stand up, or join in singing the closing hymn. Whichever external action is acceptable to your congregation will likely be helpful to your preaching.
Leighton Ford insisted that "the inner decision for Christ is like driving a nail through a board. The open declaration of it is like clinching the nail on the other side, so that it is not easily pulled out."
Whether it be internal or external, include a call for action in every sermon. Otherwise, it's not really a sermon at all. As Spurgeon said: "Where the application begins, the sermon begins."