Dinesh D’Souza in his book, What’s So Great About Christianity, while writing about the twilight of atheism talked about liberal religion in the midst of what he considers traditional, mainstream religion:
Traditional religion is the mainstream, but it is not the only form in which religion appears today. There is also liberal religion. One can hardly speak of liberal Islam, as liberalism is essentially a non-existent force in the Muslim world. But there are liberal Jews, whose Jewishness seems largely a matter of historical memory and cultural habits. Here in the West, there are lots of liberal Christians. Some of them have assumed a kind of reserve mission: instead of being the church’s missionaries to the world, they have become the world’s missionaries to the church. They devote their moral energies to trying to make the church more democratic, to assure equal rights for women, to legitimize homosexual marriage, and so on. A small but influential segment of liberal Christianity rejects all the central doctrines of Christianity. H. Richard Niebuhr famously summed up their credo: “A God without wrath brought men without sin into a kingdom without judgment through the ministrations of a Christ without a cross, (pg. 5).
D’Souza cites that liberal Christianity is retreating, one way is that the intellectual and moral ground they concede to those who are adversaries of Christianity. The second way it is retreating is in numbers. Liberal churches, by and large, are bleeding numbers and have been for years.