I have become increasingly fond of Tim Keller's writings over the last twelve months. For a Reformed pastor he has a remarkably Christ centered focus. Here are some comments of his from an article on evangelistic worship, specifically on the practice of preaching.
The one message that both believers and unbelievers need to hear is that salvation and adoption are by grace alone. A worship service that focuses too much and too often on educating Christians in the details of theology will simply bore or confuse the unbelievers present. For example, a sermon on abortion will generally assume that the listener believes in the authority of the Word and the authority of Jesus and does not believe in individual moral autonomy. In other words, abortion is “doctrine D,” and it is based on “doctrines A, B, and C.” Therefore, people who don’t believe or understand doctrines ABC will find such a sermon unconvicting and even alienating. This does not mean we should not preach the whole counsel of God, but we must major on the ABCs of the Christian faith.
If the response to this is “Then Christians will be bored,” it shows a misunderstanding of the gospel. The gospel of free, gracious justification and adoption is not only the way we enter the kingdom but also the way we grow into the likeness of Christ. Titus 2:11–13 tells us how it is the original, saving message of grace alone that leads us to sanctified living: “For the grace of God that brings salvation has appeared to all men. It teaches us to say ‘No’ to ungodliness and worldly passions, and to live self- controlled, upright and godly lives in this present age, while we wait for the blessed hope—the glorious appearing of our great God and Savior, Jesus Christ.” Many Christians are defeated and stagnant in their growth because they try to be holy for wrong motives. They say no to temptation by telling themselves, “God will get me,” or “People will find out,” or “I’ll hate myself in the morning,” or “it will hurt my self-esteem,” or “It will hurt other people,” or “It’s against the law— I’ll be caught.” or “It’s against my principles,” or “I will look bad.” Some or all of these may be true, but Titus tells us they are inadequate. Only the grace of God, the logic of the gospel, will work. Titus says it teaches us, it argues with us.
Therefore, the one basic message that both Christians and unbelievers need to hear is the gospel of grace. It can be applied to both groups, right on the spot and directly. Sermons that are basically moralistic will be applicable only to either Christians or non-Christians. But Christocentric preaching both grows believers and challenges nonbelievers. If the Sunday service and sermon aim primarily at evangelism, they will bore the saints. If they aim primarily at education, they’ll bore and confuse unbelievers.