“The Nazification of German culture showed up the fatal vulnerability of any form of Christianity that took its lead from contemporary cultural norms. Since liberal Protestantism mirrored the norms of contemporary culture, it had no adequate basis for critiquing that culture. Protestant writers such as Karl Barth and and Dietrich Bonhoeffer vigorously opposed this trend, arguing that Christianity and the churches should seek their norms and legitimation in Jesus Christ and the Bible, not in cultural norms. But they were a decided minority.”
Alister McGrath, writing on liberal Protestantism in Germany in the Nazi era, in Christianity’s Dangerous Idea. Emphasis mine.
*Note: I do not agree with the author at all points in this book, but found this particular paragraph (among many other parts) very helpful.