A very interesting question. There was a recent study published as Soul Searching: The Religious and Spiritual Lives of American Teenagers published by Oxford University Press. There was also a DVD – Soul Searching: A Movie About Teenagers and God – that has been released summarizing these findings. I watched the DVD yesterday and it was enlightening and honest. Those who work with youth, are parents of teenagers, or have children heading towards their teenager years would find this DVD interesting.
There are about 33 million teenagers in America. A third are deeply religious, a third are kind of religious, and a third are not religious at all. This study talks about each group and what impact how seriously teenagers take their spiritual lives has upon overall flourishing as people.