T. David Gordon identifies one issue with many sermons: the man preaching the sermon does not know how to read.
It’s almost as though a version of Microsoft Word were built into [preachers’] brains that causes them to see some of the words in a biblical paragraph in boldface, as the theologically, spiritually, or morally important words stand out in bold from the rest of the paragraph. They read John 3:16 the same way they read Romans 5:8; each is “about” the love of God, but they don’t notice much more than that, and their sermon on God’s love from John 3:16 is probably not different from their sermon on God’s love from Romans 5:8. Thus, they never really notice (and therefore do not and cannot preach) the distinctive thing affirmed about God’s love in John 3 or Romans 5. All of [page break] their sermons are about Christian truth or theology in general, and the particular text they read ahead of time merely prompts their memory or calls their attention to one of Christianity’s important realities (insofar as they perceive it). Their reading does not stimulate them to rethink anthing, and since the text doesn’t stimulate them particularly (but serves merely as a reminder of what they already know), their sermon is not particularly stimulating to their hearers.
T. David Gordon, Why Johnny Can’t Preach (46-47)
The man preaching the sermon does not know how to read the passage he intends to preach. Instead, he treats the passage as though it were a memory-recall device. The “important” words remind him of concepts he already knows, and these concepts form the basis of his sermon. In doing this, the man fails to allow this passage to say its distinctive thing to him, and thus fails to preach this distinctive passage.