Jenkin’s brings up an interesting point that I wasn’t aware of. I’d always had the impression that modern liberalism was a 20th century invention, contra Machen, contra pre-war conservatism. Driven largely by evolutionary biology, it came to dominate political discourse and undermine the “mainline” churches in the 1960s. It turns out though, that all of this stuff had arisen 100 years before… and been subsequently smacked back into oblivion. Secularists today honestly think the church is on the brink of becoming completely insignificant. But they thought that last time too, and the time before that. Yawn.
The rationalism prevailing in many Protestant churches was overwhelmed by a new evangelical revivalism, which received an enormous boost from the revivals that began in 1798. Far from dominating the American scene, Unitarian-Universalists today comprise around 0.2 percent of the U.S. population. So thoroughly was eighteenth-century liberalism obliterated that many modern writers tend to assume that its ideas were invented anew by Victorian skeptics and rationalists, or perhaps grew out of the controversies over Darwinian evolution. Then as now, the triumph of secular liberalism proved to be anything but inevitable.
-Philip Jenkins, The Next Christendom, p.11