This is my take on the future of American Christianity. I emphasise that it this just my personal opinion and is based on my believe that America is 70 to 80 years behind what New Zealand and possibly Britain are, and is like these countries in the forties and fifties. The USA is noted outside of the USA as being very churchy, unlike Britain and NZ. I think the USA will soon follow Britain and NZ and fall to a church going percentage of the population of about 8%, though a higher percentage will profess Christianity on a census for example. This will happen I believe because of three main trends in society. 1 Many people believe in Christianity because people tend to believe something is true if everyone has always said it is true. Does the bathwater go down the plug hole in a different direction in the Northern Hemisphere as opposed to the South? (not necessarily).Is glass really a slow moving liquid? (No). Did Moses take seven pairs of clean animals and two pairs of unclean animals aboard the Ark? (No).It is only when people start to doubt something (eg. a steady state universe as opposed to the big bang) that a belief system can crumble. And people have started to doubt Christianity. 2 Unlike most other countries it is probably socially approved, acceptable and advantageous to be a Christian in the USA. Here in NZ is is a complete non issue, probably unlike the fifties here when the non religious were looked at sideways. You can tell being a Christian is advantageous in the USA when you see Presidents and Contenders invoking the name of God. No other leaders seem to do this apart from the Ayatollahs of Iran. Probably the social advantage aspects of Christianity will decrease. 3 Society is generally moving in a direction that makes it harder for Christianity to thrive. The dead becoming alive again is hard for many to swallow. Miracles of the large Biblical type seem to have disappeared and been replaced solely by medical miracles. The supernatural world seems to be in decline: fairies, trolls, sprites, leprechauns, and elves, have mostly gone. Only ghosts and God seem to be in a relatively strong position. Many in the modern world baulk at the notion that God doesn't approve of the life style of gays or approve of women being ministers. Some Christians can of course take the moral high ground on these issues but will it result in bums on pews?
Our regions are very large and diverse here. Point 2 is not as applicable in, for example, the Northeast or West Coast as some other regions. The greatest variable for the religious future of my country is the high rate of Latino immigration. These people are culturally Christian but not necessarily well informed in any particular version of the faith. Of course, I have had doubts about how useful academic theology is to the average church goer for some years. Most are just not particularly curious and inquisitive. As long as baby Emma gets baptized, the service doesn't change too much, and Grandma gets a nice funeral most people are fairly happy with their church. Good coffee is also a plus.
I think you are giving the USA far more time left as a Christian nation of the world. I see much progress of the NWO everywhere. Governments of the world all seem to be hellbent on giving up sovereignty and becoming part of a world-wide community governed by the elite. The current government of the USA is already spoon-feeding its citizens promises that the WHO and the UN truly are in our best interests. I am old-school nationalist. I do not wish to see any more movement to those ends in my life-time and there is not much of that left, so I have little to worry about. One sees even the Pope speaking of One World Religion when speaking of unity. That frightens me.