Here's the last paragraph of Christian Smith's essay, "On 'Moralistic Therapeutic Deism' as U.S. Teenagers' Actual, Tacit, De Facto Religious Faith":
It appears that only a minority of U.S. teenagers are naturally absorbing by osmosis the traditional substantive content and character of the religious traditions to which they claim to belong. For, it appears to us, another popular religious faith--Moralistic Therapeutic Deism--is colonizing many historical religious traditions, and almost without anyone noticing, converting belivers in the olds faiths to its alternative religious vision of divinely underwritten personal happiness and interpersonal niceness... We can say that we have come with some confidence to believe that a significant part of 'Christianity' in the United States is actually only tenuously connected to the actual historical Christian tradition, but has rather substantially morphed into Christianity's misbegotten step-cousin, Christian Moralistic Therapeutic Deism. This has happened in the minds and heart of many individual believers and, it also appears, within the structures of at least some Christian organizations and institutions. The language--and therefore experience--of Trinity, holiness, sin, grace, justification, sanctification, church, Eucharist, and heaven and hell appear, among most Christian teenagers in the United States at the very least, to be being supplanted by the language of happiness, niceness, and an earned heavenly reward. It is not so much that Christianity in the United States is being secularized. Rather more subtly, either Christianity is at least degenerating into a pathetic version of itself or, more significantly, Christianity is actively being colonized and displaced by a quite different religious faith.