My view is that the reason youth are largely disinterested in the evangelical church once they “grow up” is that the evangelical church has largely been co-opted from its mission by excursions into right-wing political action.
Let me give a personal example. When I was a teenager in the 60’s, raised in a rural Southern Baptist church, the church sold its soul to the political agenda of racial segregation. That morally bankrupt idea crippled the church.
Today, evangelicals are just beginning to wake up to the fact that they have been duped on environmental issues. They’re on the morally wrong side of stem cell research. They promote crank science like young earth creationism and flood geology. They say on TV that God has a plan for you to get rich. Evangelicals tolerate character assassination and lies from the political leaders they elect.
Rather than making Christ’s love known to the world, they show the greedy, prejudiced, and intolerant face of the Republican Party.
Don’t get me wrong. There are many fine evangelical Christians, but they aren’t the public face of the movement.