Kids love rock music, and, being poor for the most part, they like events that are free. This brings in lots of unsuspecting teens. Then, either during or at the end of the show, the band will stop and the preaching will begin. Kids who would not normally go to a church suddenly find that the church has come to them. And parents who don't want their kids to be instilled with the values of the Religious Right are nowhere around to protect them.
Some groups even block the exits to keep people from leaving during the sermon.
This is where they ask these kids, now in the spotlight and under pressure from the other Christian kids, to come forward and choose a new lifestyle, one replete with the church's morals and values. The pressure is enormous, and many kids who would otherwise reject such beliefs find themselves going forward to proclaim something they don't fully understand. An extreme version of this happened recently in Colorado Springs, home to a large number of Religious Right organizations like Focus on the Family. A Baptist church hosted a carnival for neighborhood children. While at the carnival, and without their parents to intervene, kids were pulled aside and told they would go to hell unless they were baptized in the church.