There are few subject related to public ministry more critical than preaching. Here are three quotes I’ve found from some of my favorite theologians on the subject:
The size of the text is immaterial, so long as it is biblical. What matters is what we do with it. Whether it is long or short, our responsibility as expositors is to open it up in such a way that it speaks its message clearly, plainly, accurately, relevantly without addition, subtraction or falsification. In expository preaching preaching the biblical text is neither a conventional introduction to a sermon on a largely different theme, nor a convenient peg on which to hang a ragbag of miscellaneous thoughts, but a master which dictates and controls what is said.
Whatever the reason, however, the results are unhealthy. In a topical sermon the text is reduced to a peg on which the speaker hangs his line of thought; the shape and thrust of the message reflect his own best notions of what is good for people rather than being determined by the text itself. . . In my view topical discourses of this kind, no matter how biblical their component parts, cannot but fall short of being preaching in the full sense of that word, just because their biblical content is made to appear as part of the speaker’s own wisdom. . . That destroys the very idea of Christian preaching, which excludes the thought of speaking for the Bible and insists that the Bible must be allowed to speak for itself in and through the speaker’s words. Granted, topical discourses may become real preaching if the speaker settles down to letting this happen, but many topical preachers never discipline themselves to become mouthpiece for messages from biblical texts at all.
J.I. Packer, The Preacher and Preaching: Reviving the Art
To me still, I must confess, my text selection is a very great embarrassment. . . . I confess that I frequently sit hour after hour praying and waiting for a subject, and that this is the main part of my study; much hard labor have I spent in manipulating topics, ruminating upon points of doctrine, making skeletons out of verses and then burying every bone of them in the catacombs of oblivion, sailing on and on over leagues of broken water, till I see the red lights and make sail direct to the desired haven. I believe that almost any Saturday in my life I make enough outlines of sermons, if I felt the liberty to preach them, to last me for a month, but I no more dare to use them than an honest mariner would run to shore a cargo of contraband goods.
C.H. Spurgeon, Lectures to My Students