I've had several conversations in the last few days about why at our church (and other gospel-centered churches) preachers do not tell congregations, very specifically, what to or what not to do (or how to, or not to, do something). Here is why.
Let me use the example of offensive language (since I used a marginally offensive word in a sermon recently, as I was told :)). Say I preached a sermon with this title: "Words That Should Never Come out of a Christian's Mouth." And I produced a list of the kinds of language Christians should never use, all with biblical quotations to back up why this or that word or phrase is inappropriate or downright evil. I might even go on to say how bad people are who use such language, and they ought to watch out, for, referring to James 3:6, the tongue is "set on fire by hell itself."
Such a sermon would have one of two consequences in those who heard it:
First, there would be those who are not in the habit of using such words. They would hear this sermon, and think to themselves, "I got that box checked. I don't use such language. Whew! I must be a good Christian." In other words, it would produce a Pharisee.
Second, there would be those who are in the habit of using such language. They would hear the sermon and say to themselves, "Man, I just can't do it. I might as well give up. I'm never going to be able to stop swearing. I must be a horrible Christian. Maybe I'm not a Christian at all." In other words, it would produce a drop-out.
Pharisees and drop outs. Neither group would be affected at all by the gospel. The Pharisee is self-righteous, and sees no need for the gospel. The drop-out is crushed, and sees no hope in the gospel. I have not, therefore, preached the gospel at all, no matter how "practical" my sermon, no matter how easily I can go to work on Monday and "apply" it to my life.
But there is another reason why we don't preach sermons whose main points are "how-to" or "what-to." It is because when God's Word gives God's commandments, they are never such as can be directly "applied" on Monday morning, to our complete satisfaction. God never commands us things like, "don't leave home without kissing your wife as you go out the door." That would be doable, so that if I did that consistently I would have reason to feel self-righteous. No, God gives us big commandments like, "Husbands, love your wives as Christ loved the church and gave himself for her." Kissing my wife every time I go out the door may be a good thing, and may be consistent with that commandment, but the commandment is much, much too big for me to ever feel like, "I got that box checked off! I must be a good husband!"
That's why we always preach the gospel. That's why we never preach God's commandments without a strong dose of the gospel (by which our righteousness, our boasting, is found in Christ and him alone because he died and rose again). God's commandments are so big that they deal not with externals, but with our hearts. And our hearts are so warped that nothing short of the gospel of Jesus' death and resurrection has any hope of giving us any assurance, or of giving us hope that we might ever change for the better--or make progress toward keeping God's big commandments. For we always need gospel forgiveness, and gospel change. And that is what, above all, we preach.