To my knowledge there is no religious group that fits the description I have given. Nonetheless, I believe that the religion I have described is viable today in America, and once introduced could rise to dominance within fifty years. This is extraordinary speed for a religious revolution, but it is possible because the triumph of the next religion will not require conversions of Pentecostal magnitude. Our existing churches are filled with people who have a "yes, but. . ." relationship with the dogma of their denomination. They go along up to a point, but then they go off on their own. This is for many a guilty secret or a source of embarrassment. Such people will find that they can better practice their religion in the new church than in their current one. They could believe what they already believe, say what they think, and be welcomed. Similarly, couples with religious disagreements could join the new church together and both be supported. Groups of friends would be able to join the same church without first hammering out a common creed. Once started, such a process could spread with the speed of a virus.
There are several ways that the next religion could come about. It could be popularized by a charismatic teacher. It could be envisioned by a popular novelist and started by his readers. (The Church of All Worlds, for example, is a small religious group patterned after the belief system in Robert Heinlein's Stranger in a Strange Land.) Or an existing church could evolve to fill the waiting niche.
The third possibility is the easiest to imagine. The most likely candidates are the liberal Christian denominations and the Unitarian-Universalists. These groups have a history of theological evolution and an acceptance of new ideas. Moreover, they find themselves in an identity crisis. In the public mind the word "Christian" has been taken over by the fundamentalists. (When Pat Robertson ran for president, for example, his followers referred to him as "the Christian candidate". The media did not challenge this assertion.) Having freed themselves from many of the dogmatic aspects of Christianity, they often find themselves without a firm foundation for the beliefs and practices they want to keep. They have an intuition of what it means to be a good community, but the metaphors and symbols of their Christian tradition do not allow them to state this vision in a way they can be proud of. Their non-authoritarianism comes off as wishy-washiness or moral uncertainty. Their tolerance appears to be a lack of standards, their open-mindedness a lack of conviction. They cannot help but envy the certainty and zeal of the fundamentalists.
But a liberal church that could take the bold steps of adopting the ecological metaphor, focusing on experience, welcoming polytheism, and teaching the joyous aspect of morality would find that its identity crisis was over. It could stop explaining why it no longer is what it used to be, and could focus instead on becoming what it wants to be. But let us not underestimate those bold steps. The hardest thing of all for a liberal church would be to focus on experience. Of all religious groups in America, these are the ones that are most infected with Scientism. They are suspicious of myth and ritual, and they are very suspicious of religious experience. They have left the born-again experience behind them, and have toned Jesus down from a charismatic miracle-worker and mythic hero to a teacher of ethics on a par with Socrates. For a liberal church to convert to the next religion, it would have to convince itself that religious experience is possible, that it is not a form of insanity, and that it is desirable. Perhaps this is asking too much.
But whether any of the liberal churches seizes the opportunity or not, the fault line is still there and the quake will come. Individuals are creating the next religion on their own. It is only a matter of time before they find each other and start a church.