My 15-year-old son likes anime with philosophical content and it is fun to read about philosophy and religion on tvtropes.org. My son picked out a book on world religions last week at the bookstore after reading "30-Second Religion." He has read philosophy books also but I don't remember the names of the books. We also bought "The Everything Gnostic Gospels book" and it is very interesting. We are reading and discussing it together. I did not study philosophy at all until my son became interested in it several years ago.
