According to the New York Times, after a period when it was more fashionable to study relatively marginalized religious movements like evangelicalism and Mormonism, historians are turning their attention back to liberal mainline Protestantism. One of the more surprising arguments, made by David Hollinger, is that the legacy of the mainline may be deeper and more enduring than its numerical decline suggests. He contends that, despite the apparent success of conservative evangelicalism in displacing it from the center of American Protestantism, liberal Protestantism succeeded in imparting certain broadly progressive values to American society.

Perhaps providing some support for Hollinger’s thesis, a report released this week by the Brookings Institution and the Public Policy Research Institute suggests that the religious conservatism in America is actually declining, and progressivism is on the upswing. The report summarizes the results of a survey of Americans’ views on economics and religion, and a key finding is that younger generations are more likely to identify as religiously moderate or progressive (or not religious for that matter). This trend seems to mirror the same long-term demographic changes that are contributing to the woes of the Republican Party. In short: America is becoming less old, white, and conservative and more young, non-white, and liberal.

Of course, “conservative,” “liberal,” “progressive” and the like are notoriously slippery and malleable terms (particularly when it comes to theology). And we don’t know if increased religious liberalism will translate to a revival of more progressive religious communities. At the same time, though, these trends hardly seem to support the oft-repeated claim that hard-core theological conservatism is the key to successful, growing churches.