I say this as a great admirer of Barth, but I’ve always found the “theological” critique of Nazism to be weirdly disconnected from reality. For instance, Barth’s self-congratulation that the church somehow did the right thing insofar as a small sect of it rejected natural theology in the midst of Nazism strikes me as downright chilling. The test here is that you could take it the opposite direction: for instance, the lack of a viable natural theology produced a disconnect between the gospel and the world, which led to the unlimited rise of technological instrumentality that was then ultimately turned against the human race itself most horrifically in Nazism, etc. Or you could say that the artificial either/or of Christ or nature led necessarily to the embrace of natural “paganism,” etc. Or basically you could make up any “theological” cause you like and congratulate yourself for bravely coming down on the right side of the debate, but that doesn’t make what you’re saying relevant. If anything, wouldn’t it have been more immediately relevant and more obviously connected to Nazism if the church had staked its identity on the opposition to anti-Semitism rather than the somewhat obscure point of natural theology?