I think it may be possible to say that every sermon should have three aspects or purposes. First, you need to preach the text in its scriptural context; second, you need to preach Christ and the gospel every time; and finally, you need to preach to the heart. Put another way, you should preach the truth, not just your opinion; you should preach the good news, not just good advice; and you should preach to make the truth real to the heart, not just clear to the mind. The first is often discussed under the heading of expository preaching, the second is often called Christ-centered preaching, and the third is usually named "application" (though I think each aspect contains more than these traditional categories might imply).
In that schema, where does "cultural engagement" come into my sermons? Most people would say that it does not fit into the scheme—preach the text, preach Christ, and preach to the heart. They might be tempted to add a fourth category. But that might suggest that cultural references are principally there to give the preacher some personal credibility. That would be a mistake. To make references for that purpose would tempt you to basically show off your learning or maybe your cultural hipness. That is not what I'm trying to do.
You might be surprised to hear me say that my use of cultural references is actually part of my effort to reach the heart. But, you may respond, aren't those references to Nietzsche or de Kooning highly intellectual, designed to appeal to the mind and not the emotions? Not exactly. One of the keys is in how we define "the heart." Remember that according to the Bible, the heart is not primarily the emotions but rather the seat of our fundamental commitments and trusts, and therefore it is the control center of the whole life. So to preach to the heart means to go right for the commanding commitments of people's lives that drive their desires, thinking, feeling, and action.
There are many working definitions of "culture," but I think one of the best is that culture is a collective heart. It is a set of commanding commitments held and shared by a community of people. My hearers—both Christians and non-Christians—live in the highly secular, late modern (some would say postmodern) cosmopolitan culture of Manhattan. This ethos is pulling on the hearts of all its residents. It is the source of so many of their deep aspirations, unspoken fears, and inner conflicts.
The "cultural references," then, are simply my way of entering the world of my hearers, helping them understand at a deep level what is shaping their daily work, their romantic and family relationships, their attitudes toward sex, money, and power. I seek to make plain the foundations of our city's culture in order to help people understand themselves more fully and imagine what it means (or would mean) to live as a Christian here.
So it would be a mistake to merely imitate any preacher who makes a lot of cultural references in his sermons. In many parts of the world, citing Kierkegaard is not all that unusual, and if done rightly can lead people to say, "Oh, so that's why I tend to think and feel that way." That's what you want to achieve. But in many other parts of the world it might only make people say, "Wow, he's really intellectual and smart." If that latter response is what you get from people (or worse yet, what you want from them) then you need to make some changes. The universal principle is found in Acts 2:37—preaching must "cut to the heart." The means and methods we take to get to that end depend a lot on, well, your culture.
Editors' Note: This is a cross-post from Tim Keller's blog at Redeemer City to City.