I find that expository preachers often do not really ask, What's the purpose of this sermon? What should it do in people's lives? If you say, "Why are you preaching on Romans 5?" some preachers answer, "Well, because last week I was in Romans 4. Next week I'll be in Romans 6."
Until we have figured out why the passage would be important to people today — not just tell them that but show them that (e.g., How would it work in their business? How would it work in their homes? How does it work in their thinking?) as we bring the biblical text and the modern world together — we haven't done our job.
So we are not preaching to people about the Bible. We are preaching to people about them from the Bible. And that means that there are two tensions: the tension of the biblical text (crucial, vital, and important) and the tension of the folks who are listening to us. Good preachers work has to see to it that their sermons have that balance of biblical truth and contemporary relevance. That's why being biblical and contemporary is the art of Christian communication.