If you are going to preach an effective sermon you must follow Cleophus LaRue’s next principle of effective sermons which is A Fitting Close to the Sermon
Some argued that the sermon should always end in celebration. Others argued that it should have a “fitting” close. In any case, the sermon close should not be an irrelevant tack on to the main sermon. All that will do is obliterate the message from the minds of the hearers.
One should celebrate in some conclusions and challenge in others. However, I think an interesting variant is one thing that I heard Dr. Brad Braxton do effectively which is to “celebrate the challenge” or have a “celebratory challenge.” In this variant the preacher challenges the congregation and then celebrates the fact that they all will do it or they all will take steps towards accomplishing that which is challenged.
For example, in my sermon “God Still Speaks” which you can find at this link. I have a celebratory ending. However it is also a challenge. I celebrate that going into the Jordan cleans you up. And then I tell folks that I am going into the Jordan River. Then finally, I ask the people to go down into the Jordan with me. A celebratory challenge that really fits nicely as an appeal.
Having in mind how you will close will increase the effectiveness of your sermons.