Expository preaching is that which explains the author's intent in a specific Bible passage and applies that intent in our cultural context. Expository preaching means God's word is in the driver's seat for each sermon or lesson. Whatever the verse says, we must say. Whatever the flow of logic is, we must be carried by it. Whatever the emotion of the text conveys, we must likewise be moved.
When we do this, God's voice is heard. It is as authoritative as if God were speaking it Himself in our midst. This is the centerpiece of the church gathered.
Therefore, we preach through books of the Bible verse-by-verse. In doing so, we are kept from skipping challenging passages, riding hobby horses, and falling into the typical imbalances of topical preaching. While avoiding those errors, we are richly fed on the pure milk of the Word as God has given it to us.