My book, Soul Searching: The Religious and Spiritual Lives of American Teenagers (Oxford University Press, 2005), co-authored with Melinda Lundquist Denton, follows over hundreds of pages a variety of topical trains of thought and sometimes pursued diversions and digressions. But what does the bigger picture of the religious and spiritual lives of US teenagers look like when we stand back and try to put it all together? Here we re-summarize our observations in venturing a general thesis about teenage religion and spirituality in the USA, tentatively advancing this thesis as something between conclusive fact and mere conjecture. We suggest that the de facto dominant religion among contemporary teenagers in the USA is what we call ‘Moralistic Therapeutic Deism’ (MTD). This ‘religion’, which emerged from hundreds of interviews with US teenagers, consists of a God who created and orders the world, watching over human life on earth. This God wants people to be good, nice, and fair to each other, but does not need to be particularly involved in their lives, except when he is needed to resolve a problem. Being happy and feeling good about oneself is the central goal in life. When they die, good people will go to heaven. These tenets form a de facto creed that is particularly evident among mainline Protestant and Catholic youth, but is also more than a little visible among black and conservative Protestants, Jewish teens, other religious types of teenagers and even many ‘non-religious’ teenagers in the USA. Note that no teenager would actually use the terminology ‘Moralistic Therapeutic Deist’ to describe himself or herself and very few would lay out the main points of its creed so clearly and concisely. Rather, it is our summarizing term for the religious viewpoint that emerged from hundreds of interviews on matters of religion, faith, and spiritual practices. While quotes illustrating MTD are aplenty, suffice it here to examine merely a few that are representative of this religion’s core components.