Skye Jethani has written a very thought-provoking article on the Out of Ur blog. Here's a quote:
"Seeking survival and fearing irrelevance, have we clothed our faith with the forms of our American culture to the point that our Christianity has morphed into something entirely different—a folk religion altogether consumerist in spirit and content?"
This is an interesting question, but I think it's the wrong question. Is there a folk religion in the U.S. masquerading as Christianity? Without a doubt. When 80+% of the population self-identifies as Christian, there's clearly some poor definitions of Christianity being used. The real critical question is, what is the cause? I don't think survival and relevance are the issues.
I suppose you could say it's semantics but as I define it, relevance is not evil even though some treat it as such. It can be overemphasized but that's a symptom, not the disease. Relevance in proper balance is simply communicating and applying the Gospel to an existing culture. This is what Paul did on Mars Hill, it's not a new phenomenon indicating the arrival of Laodicea.
The real problem is not a desire for relevance but a desire for comfort. We want to be comfortable in our world, and we want our world to be comfortable with us. We want to live just like our neighbors so they won't feel uncomfortable around us and we'll feel accepted. Too often faith is compromised for the sake of fitting in. Peer pressure is not just a problem for teenagers, it's just as bad or worse for adults. We must realize that this world will never be comfortable with the message of Christ, and we cannot be (or shouldn't be) comfortable in this world. I don't think we need to beware relevance OR irrelevance. We need to beware becoming comfortable. If we become comfortable, we cease to be salt and light.
I'm not saying we need to go back to the days of Holiness legalism just so we can make people uncomfortable. That's not the kind of discomfort I'm talking about. We're not called to find creative ways to make people uncomfortable around us. We're called to be Christ-like by loving, sacrificing, healing, caring, giving, praying, and worshipping. If we can even come close to accomplishing that, it will create plenty of appropriate discomfort.