A list from Focus on the Family's Jim Daly's Blog on reasons kids leave the church:

10. The church is “relevant.”
Normally, “relevant” is a positive term. In this case, it labels the problem. We’ve couched our faith in modern trappings to the point that 2,000 years of history and rich tradition have been diminished. As the article suggests: “What we’re packaging is a cheap knockoff of the world we’re called to evangelize to. In our effort to be ‘like them,’ we’ve become less of who we actually are.”

9. They got into church, but the church never got into them.
Many young adults may have been taken to church by their parents, but the church wasn’t integrated into the fabric of their lives. Church was a Sunday event, not something that impacted the everyday realities of their lives.


8. They were treated as smart by others.
Many students interviewed felt they were spoon-fed a Christian worldview, while professors and others who held atheist viewpoints challenged their intellect and inspired them to ask questions and to use their mind.

7. They were sent out unarmed.
Many youth have mastered Christian lingo – the pithy catchphrases spoken regularly in churches and marketed through popular evangelical campaigns – but they’re ignorant of deeper theological truths. They know what “WWJD?” means, and they’re familiar with how to “invite Jesus into your heart,” but they can’t explain what atonement or justification means or its relevance to life’s realities.

6. They’ve been given a “hand-me-down” religion.
Many kids leave the church feeling like they’ve been asked to accept their parents’ faith, instead of encouraged to ask tough questions, so they can incorporate Christianity into their lives and make it their own.

5. They exchange one community for another.
Our modern faith sometimes places a greater emphasis on community than on God. As a result, many of today’s youth see other people as the answer to their problems instead of God. When they leave home, they often seek out a community of people of any belief system rather than one committed to the God of the Bible.

4. They seek opportunities to “feel” better.
Much of modern Christianity is based on “feeling,” rather than on objective, eternal truth. It reduces the Christian faith to a search for good feelings rather an exhortation to conform our human nature to God’s standard of righteousness.

3. They got tired of pretending.
Some segments of Christianity suggest that being a Christian removes all struggle from life. But that message rings hollow for many kids who try to serve God and continue to face difficult challenges … or who see their parents teach a similar message while succumbing to anger or depression themselves. Many youth feel Christianity leaves no room for authenticity.

2. Christianity is reduced to “do/don’t do” instead of “be.”
Many church kids were taught it’s all about what they do, not who they are. The Christian faith was reduced to a long list of do’s and don’ts. They felt trapped beneath the weight of their own abilities, instead of freed by the work only God can do in their hearts and lives.

1. They don’t need it.
When church is perceived as nothing more than a place to learn good principles for living, or to have a happy marriage, or well-behaved kids… Well, you can find that in most any self-help book. You don’t need a crucified Jesus for that. What kids need is the gospel; what they’re sometimes given is “a cheap knockoff of the entertainment venue they went to the night before.”
 

Read Jim Daly's compleate blog post here