Your "Death of Christianity" page does not address the question of what KINDS of Christianity are shrinking, vs. what KINDS of Christianity are growing.  Your sole focus seems to be on the growth of both atheists and "Nones."

What's shrinking is middle-of-the-road Christianity.  On the other hand, the wilder and crazier forms of Christianity -- e.g. the "non-denominational" independent charismatic churches, some of whom have explicitly theocratic ambitions -- have been growing rapidly, both here in the U.S.A. and, even more so, in Africa, Asia, and Latin America.  (And they are coalescing into organized networks such as the "New Apostolic Reformation.")

So it seems to me that, for at least the next century or so, the overall direction that the U.S.A. is moving in is, alas, NOT toward a nice liberal European-style humanistic society.  Rather, we're moving toward ever-fiercer polarization between thoroughly obnoxious Christian fanatics and everyone else.