Seven out of ten kids who are churchgoing at age 18 aren't by age 30.
I could mention oodles of ways in which the church is 'irrelevant' to today's culture, but other people are better at complaining about that than I am.
The cliché response from the church to culture losing interest is to become more fundamentalist. Some churches see that the kids have quit going to church and started square dancing on Saturday night, so they start teaching that square dancing is sinful, it must be, because why else would kids stop going to church?
I've seen a more nuanced response in movements like the contemporary church, emergent church, and seeker-sensitive movements. These movements make it harder for me to believe that God exists.
I suppose these movements have diverse roots, but it seems that the theory behind all of them is that people aren't interested in Christianity because they're not aware of how it relates to their lives.
The phrase 'felt needs' pops up a lot. Back in the sixties, it was more common in evangelism to start the sales job with explaining to marks that they are sinners and are thus damned, and finish with a message about how Jesus will save them from hell if they become Christians.
These newer movements drop the first part of the sales job, because most sinners evidently don't feel like sin is their top problem. The modern strategy is to figure out if someone's looking for community, or healing, or entertainment, or financial stability, and then show them how Jesus can give them that.
If we can make Christianity look more like Pacific Northwest hipster spirituality with yoga mats and candles and incense and craft beer, so much the better.
This doesn't work as well as you'd think.
If you have a non-Christian friend you're trying to convert, and he drinks fair-trade coffee and is militant about recycling, the new strategy is to tell this friend about how Jesus is a militant environmentalist and social justice guru, which is true, but telling people about what Jesus likes isn't the same as encountering Jesus.
There's not a lot of magic to meeting felt needs. Christianity has to give a better sort of peace than can be had from meditation or aromatherapy. Christianity can't just meet a human need for community; people make clubs about tea and model railroads and knitting, we socialize based on who we're related to and where we live. Christianity must lead to an altogether different kind of community. Christians should use knowledge from psychology to heal people's souls, but Christianity has to provide a healing that psychology can't explain.
Relative to Jesus, things like aromatherapy, the Rotary Club, and talking cures are smaller and safer and more believable. Jesus is impossibly hard to believe in and he requires extreme things of us. If you're looking for fulfillment or esteem or peace, Christianity is probably not the shortest path to those things; at least, Jesus didn't seem to think so.
When a non-Christian finds their felt needs met in the church rather than in Jesus, this is a tragedy. If the church makes it too easy for outsiders by fulfilling their felt needs, they might stop short of a dangerous and real relationship with God.
Grandma doesn't have a good marketing department, she doesn't wear cool clothes, she doesn't listen to indie music, she doesn't have a trendy haircut, she's afraid of computers. She used her microwave as a breadbox. I wouldn't have it any other way, because Grandma and I love each other. Movements in Christianity that respond to culture's indifference to the church by trying to make Christianity more relevant scare me, because the church's job isn't relevance, its job is to be God's house, and God is content with living in a tent. The church's job isn't to make God exist, that's God's job. If God is real, our response to culture's loss of interest in the church ought to be faithful reliance on God to demonstrate himself on his own terms. It isn't.