You do need the Holy Spirit when you preach. No argument there. There’s a work that only the Spirit can do while you can’t—and that is to impact the hearts of people and change them to become more like Jesus. However, the Holy Spirit is not all you need. If such were the case, you might as well forgo sermon preparation, step on stage on Sunday morning, and hope that the Spirit will instantly give you something to say in the next thirty minutes. Some preachers may operate that way and I admire their abilities. However, for the rest of us, we need to carve out time during the week to prepare well for a sermon. And I wholeheartedly believe that God honors our skillful preparation and presentation.
If you’re going to engage in any sort of preparation, you might as well do it skillfully by taking advantage of some of the best methods out there. Some will argue that using speaking methods goes squarely against reliance on the Spirit. I couldn’t disagree with you more. Here are two people that made use of common speaking methods but were also evidently filled with the Holy Spirit.
(1) Jesus. Surprisingly (or unsurprisingly, I should say), Jesus is one of the clearest examples of being filled with the Spirit (Luke 4:18) but also making use of speaking methods to make his messages clear and memorable. He deliberately chose locations where his voice could be echoed through the crowd so that everyone could hear him—sort of like a natural microphone. Those locations included mountainsides and near bodies of water (Matt. 5:1; Luke 5:1-3). Jesus also used plenty of stories (called parables) to drive home key truths. The use of stories is an old but still very popular method to make points incredibly memorable.
(2) Paul. Although we don’t have records of Paul’s sermons, we do have his letters which are filled with various literary methods that aided him in getting his ideas across. Paul didn’t shy away from using illustrations such as the human body to metaphorically represent the members of Christ’s body (1 Cor. 12:12-27). He also frequently asked questions in his writings to provoke thought from the audience. Then he would answer his own questions to fill in the knowledge gap that was created (read the book of Romans for plenty of examples).
When it comes to reliance on the Holy Spirit and the human skill we put into our sermons, it’s not a choice between the two. I believe both aspects work in harmony to produce God-honoring sermons. Depend squarely on the Holy Spirit for powerful results but, at the same time, go ahead and use speaking methods to communicate clearly and memorably.