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I have found a rather wide-range of understanding about what ‘expository preaching’ means. A common definition of exposition is “The communication of the meaning of a passage of Scripture (usually an extended passage of several verses) along with its relevance to present-day hearers with a view to spiritual maturity and change.” A common definition of expository preaching is: “Expository preaching is the communication of a biblical concept or an extended portion of Scripture, arrived from and transmitted through a historical, grammatical, and literary study of a passage in its context, which the Holy Spirit first applied to the personality and experience of the preacher, then through him to this hearers” (Taken in part from Haddon W. Robinson, Biblical Preaching, Baker Book House, Grand Rapids, 1980, p. 20).
This in itself does not define for us the precise method one might use and could be applied to a lot of different methods. Expository preaching can be very detailed or it can highlight the main ideas of the passage. One professor I had in seminary taught the “main idea” concept which meant we were to do our detailed exegesis in the study and then work on promoting the main idea of the passage. His thought was to leave the details in the study and just get across the main point of the text. Personally, I believe people need to see something of the method used in arriving at the meaning of the passage so they can truly understand and be convinced that is really what the text is saying. This doesn’t mean we parse every verb and decline every noun, but that we do help people see the meaning of words, some grammar when it is really important and so on.
Some expositors make excursions into other doctrinal areas in the process of teaching through a book of the Bible. This can be helpful, but if it is done too much it can have draw backs. First, it can cause people to lose the flow of the passage and its context. Further, it takes so long to go through a book that many people lose interest. The concept of Isaiah 28, “precept upon precept, line upon line” is used to support this method. So, while I think the concept has merit, I also think it must be used sparingly and wisely. There may be the need to branch off on occasions into other areas to explain certain doctrines of Scripture, but usually this can be done in a concise way without keeping you from continuing to move through the passage.
As an illustration of this, say you are working through a passage that uses the word “salvation.” Because of the many preconceived ideas floating around out there it may be necessary (depending on one’s audience) to explain the various uses of the word salvation (soteria) and explain the three phases of salvation (saved from sin’s penalty, from it’s power, and one day, from it’s presence). If the passage is dealing with being saved or with deliverance from physical sickness as a result of divine deliverance, it might be necessary to briefly cover the issue of God’s discipline and the consequences of sin. Such is really not an excursion down a ‘rabbit trail,’ but rather necessary to help illuminate a particular passage in the light of the context of the New Testament or the Bible as a whole. On the other hand, if one spends three weeks doing this, then the audience is probably going to lose the flow and meaning of the text.
Fundamentally, exposition means explaining the meaning of the text, and that will often include the need to explain the meaning of words as they are used in the New Testament (their field of meaning) and then the specific focus in the passage at hand. The point is we need to do what will help us explain the author’s intended meaning to his audience and then try to bridge the gap to our audience. It is true that a passage has one intended meaning to the original audience and many applications for us. Teachers must be careful in their applications, however, because a lot of heresy is promoted in the name of application.