it's sort of a no-brainer - kids who self-identify with a group who are generally seen in a positive light are going to feel better about themselves. a kid who feels like he fits in with the group of his choice is going to feel better about himself. a kid who feels good about herself and her social group is not going to seek out friendships with unhappy, self destructive kids. sad, miserable kids who don't fit in, who don't have a positive social group, who don't have a supportive family are at high risk of major depression, substance abuse, etc etc. It's kind of a giant DUH!! and religion/spirituality is just one type of social group. I suspect that if the effort was made to find kids who were non-spiritual throughout childhood, but had some other social group that they belonged to that enjoyed the same level of generally positive perception from the community at large, you would see the same mental health and behavior benefits.