The Bible presents an astonishingly simple method of preaching. In Nehemiah 8:8 we read that Ezra and his fellow preachers “read from the book, from the Law of God, clearly, and they gave the sense, so that the people understood the reading.”
There is no calling as majestic as the Christian ministry, and yet the central task of ministry is breathtakingly uncomplicated. We read the Bible aloud, we read it clearly, and then we explain what we have read, so that hearers understand the meaning. Of course, no one said it was easy. This is an arduous calling, but it is incredibly simple in design.
The most amazing thing about preaching is the fact that God chose to use human mouths for his message. It is astounding that God has willed that the earth shall hear his voice by means of the human voice.
Martin Luther put it this way:
“Thus when you hear a sermon by St. Paul or by me, you hear God the Father Himself. And yet you do not become my pupil but the Father’s, for it is not I who is speaking; it is the Father. Nor am I your schoolmaster; but we both, you and I, have one Schoolmaster and Teacher, the Father, who instructs us. We both, pastor and listener, are only pupils; there is only this difference, that God is speaking to you through me. That is the glorious power of the divine Word, through which God Himself deals with us and speaks to us, and in which we hear God Himself.” 
In this light, perhaps the most clarifying way to understand the preacher’s task is to consider its most quintessential act — the opening of the mouth.
Look with me to the Book of Acts, 10:30-43:
And Cornelius said, “Four days ago, about this hour, I was praying in my house at the ninth hour, and behold, a man stood before me in bright clothing and said, ‘Cornelius, your prayer has been heard and your alms have been remembered before God. Send therefore to Joppa and ask for Simon who is called Peter. He is lodging in the house of Simon, a tanner, by the sea.’ So I sent for you at once, and you have been kind enough to come. Now therefore we are all here in the presence of God to hear all that you have been commanded by the Lord.” So Peter opened his mouth and said: “Truly I understand that God shows no partiality, but in every nation anyone who fears him and does what is right is acceptable to him. As for the word that he sent to Israel, preaching good news of peace through Jesus Christ (he is Lord of all), you yourselves know what happened throughout all Judea, beginning from Galilee after the baptism that John proclaimed: how God anointed Jesus of Nazareth with the Holy Spirit and with power. He went about doing good and healing all who were oppressed by the devil, for God was with him. And we are witnesses of all that he did both in the country of the Jews and in Jerusalem. They put him to death by hanging him on a tree, but God raised him on the third day and made him to appear, not to all the people but to us who had been chosen by God as witnesses, who ate and drank with him after he rose from the dead. And he commanded us to preach to the people and to testify that he is the one appointed by God to be judge of the living and the dead. To him all the prophets bear witness that everyone who believes in him receives forgiveness of sins through his name” [Acts 10:34-43].
The context is one of the most significant turning-points in the Book of Acts. This text explains not only how Cornelius came to be saved, but how we — the Gentiles — can be saved. This came after Peter had received his vision and heard the voice from heaven declare: “What God has made clean, do not call common” [Acts 10:15].
Peter was commanded to follow three men, who took him to the house of a Roman centurion, Cornelius: “And they said, ‘Cornelius, a centurion, an upright and God-fearing man, who is well spoken of by the whole Jewish nation, was directed by a holy angel to send for you to come to his house and to hear what you have to say’” [Acts 10:22].
Dr. R. Albert Mohler Jr. serves as president of The Southern Baptist Theological Seminary – the flagship school of the Southern Baptist Convention and one of the largest seminaries in the world.