I began to answer the question, “Why preach expositionally?” here and here. Here I’d like to expand on those answers by adding another reason I think pastors ought to make expository sermons their regular practice in the pulpit.
The Original Meaning
A third reason pastors should preach expositionally is because Scripture should be interpreted and understood as it was given to the original audience. The text cannot mean today what it did not mean then. Fee and Douglas Stuart correctly assert, “A text cannot mean what it never could have meant to its author or his or her readers.” This principle does not neglect the fact that the faithful expositor must build a sturdy bridge between the historical audience and their context, and the audience he addresses here and now. It does mean he will not eisegete the text, reading into it the preconceived notions of his own imagination or interest. Further, he will not injure and impair the inspired text with a fanciful and irresponsible hermeneutic that surpasses the allegorist of the medieval period.
As evangelical expositors, we must continue to affirm that “the meaning is one, though the applications are many.” Jay Adams says, “Though the purpose of the sermon may be different from the purpose of the text, the purpose of the sermon will not violate the purpose of the text, for whenever preachers depart from the purpose and the intent of a biblical portion, to that extent they lose their authority to preach.” That is a strong word, but a necessary word. We must honor the text as it was given and as it would have been understood by the original audience.
Canon and Sensus Plenior
This principle does not ignore the divine authorship of Scripture, the concept of the whole canon, the flow and nature of redemptive history, or the intriguing issue of Sensus Plenior. As Vanhoozer argues, and I find his argument compelling, the “‘fuller meaning’ of Scripture—the meaning associated with divine authorship—emerges only at the level of the whole canon.… The canon as a whole becomes the unified act for which the divine intention serves as the unifying principle. The divine intention supervenes on the intention of the human authors. The Spirit will apply meaning, not change it.” In other words, implications and significance embedded in the meaning of the text, in light of the whole canon, may certainly come to light. This will provide balance, as well as a healthy affirmation of the principle of progressive revelation.
Preachers ought to take seriously the conviction that God was speaking in and through real men with His message for His Church. The first task of the expositor is to explain the meaning of those words as they were meant to be understood. Any application to the contemporary context must flow from that original meaning and remain consistent with the fullness of God’s revelation in all the Scriptures. When preachers ignore this original meaning or provide contradictory applications of it to their audience, they lose the right to proclaim, “Thus says the Lord.”
A version of this post previously appeared on betweenthetimes.com)
 How to Read the Bible for All It’s Worth (2003), 74.
 Quoted in Timothy Warren, BibSac (Oct-Dec 1991), 480.
 Is There Meaning in This Text? (1998), 264-65.