To be biblical a sermon must be rooted in the particularities of a passage of Scripture, in the immediate and wider context of the passage and in the cosmic sweep of the Christian gospel as a whole. Only thus can I be sure that I have heard an authentic proclamation of the Word--not just that I have admired the silver-tongued eloquence of the King's herald or even the splendor of his robes, but that I have caught a fresh glimpse of the face of the King himself. The preacher cannot guarantee that this will happen. The preaching event, that moment of royal meeting, is something we cannot create or command. Only God can do that.
At the heart of it, preaching is the telling and retelling of Christ's story and our stories from creation to parousia. It is the remembering of the stories with a special kind of remembrance of which the Bible speaks (Old Testament zakar, New Testament anamnesis), a remembrance that does not merely call to mind the thing remembered, but that makes it real, present, potent, and demanding here and now.
We must admit that simply knowing the contents of the Bible is not a sure route to spiritual growth. There is an aweful assumption in evangelical churches that if we can just get the Word of God into people's heads, then the Spirit of God will apply it to their hearts. That assumption is aweful, not because the Spirit never does what the assumption supposes, but because it excused pastors and leaders from the responsibility to tangle with people's lives. Many remain safely hidden behind pulpits, hopelessly out of touch with the struggles of their congregations, proclaiming the Scriptures with a pompous accuracy that touches no one. Pulpits should provide bridges, not barriers, to life-changing relationships.