The times when I have sensed I was merely an instrument of the Holy Spirit in preaching were times when I had planned to speak about or do something else, and during the service I felt a strong sense of the Spirit of God to go another direction. What I said was unplanned, however related to the theme of that original message. I had a revelation of what God was going to do in that service, and then once I got in that direction, the Spirit of God took hold.

And so I'm talking of spontaneity, an encounter with the Spirit of God at the preaching moment. At the end, what has been spoken to the people of God was not me. I was merely a voice through which the Lord spoke.

When I am preaching in the power of the Spirit, there is a flow. I find myself being moved along, carried along by the Spirit.

What I've had to adjust to is when I'm in a very structured service. On Sunday morning in the African-American tradition, the pattern is that the invitation to accept Christ follows the message. Some of the most powerful moves of God in our congregation have been times when the Spirit of God led me to extend that invitation in connection with a song, prayer time, or Scripture reading—before the sermon. There's fluidity in the service that I seek and try to flow with.

Many times when I have stuck closely to an original plan, what we did was more me than it was God. There have been times when I resisted the reordering of a service in order to stick with the program. That does not demean the validity of what I was saying, but I find that I'm going against the grain of where I sense the Lord would have us go.

I don't want to imply that the Spirit of God is not equally involved in our planning and preparation. I don't want to imply that extemporaneous sermon content is the norm. The norm would be that the Spirit of God is involved in the entire process of what goes on in my study Monday through Saturday. You study to show yourself approved. You dig, you prepare, you meditate. And for me that is a weeklong process, sometimes more. I primarily know on Sunday night where I'm going the next week, and so all week I'm preparing. I'm letting it simmer.

So I don't want to diminish the value of allowing the Spirit to be involved from the very beginning, but I am trying to cite instances where I have felt this divine intrusion. In the Old Testament, when the glory of God so occupied a place, the ministers could not stand to minister. I take that to mean that God stopped the program. God changed the order of worship. God tore up the bulletin that Sunday. Being involved with what God is doing makes those times dramatic and meaningful for me.

When Scripture says, "The wind bloweth where it will," it speaks of the sovereignty of God, of the authority of God not to be boxed in, limited, or taken for granted. There is an unpredictability about God. In his sovereignty, God moves according to his own counsel and will not be manipulated—or even anticipated—in some ways.

Walking in the Spirit is our response to God's sovereignty. Our desire is to be in the place where God chooses to move. That's not playing a guessing game; it is based on the directives of the Word of God. It has to do with holiness. It has to do with our submission, humility, and repentance.

I picture the preaching moment as bringing to the Lord a bowl that has been filled with my prayer and preparation from the text. Through that process this bowl is filled. At that preaching moment, I submit all of it to him, and what I find is there are times when he chooses what he will take out of that bowl. My challenge is not to get stuck on what I thought was such good stuff in there—This I have to say—and recognize that it may not be what the Spirit of God wants to do at that time.

The flip side is he not only chooses certain things out of that bowl, but he also places things directly into my mouth that I didn't plan for.

You preach the Word. That's the essence of the message, not the packaging, the alliteration, the fancy outline, but the essence of the Word. If that is your focus, the promise of God is that his Word will never return void. I have learned that Scripturally; I have learned that experientially.

Ken Ulmer is pastor of Faithful Central Bible Church in Ingelwood, California, and author of The Anatomy of God (Whitaker House).