My source is Anthony Dancer, An Alien in a Strange Land: Theology in the Life of William Stringfellow (Eugene, OR: Cascade, 2011). Dancer quotes a work from 1946 (A.R. Vidler and W.A. Whitehouse, eds., Natural Law: A Christian Reconsideration) as follows:
While many writers among the United Nations would say that the Nazis threw over the conception of a Natural Law...Martin Bormann, head of the Nazi Party organization, said: 'We National Socialists sat before ourselves the aim of living as far as possible by the light of Nature: that is to say, by the law of life. The more closely we recognize and obey the laws of Nature and Life, the more we observe them, by so much the more do we express the will of the Almighty (Dancer, 38, emphasis mine).As a number of scholars have shown, Karl Barth's vigorous repudiation of natural theology in the early 1930s and his very public and acrimonious break with other members of the dialectical theology circle was driven largely by his strong political opposition to National Socialism: In other words, Barth was deeply worried that any form of natural theology or any appeal to a "point of contact" between the Gospel and some ostensible human capacity for revelation would serve to aid and legitimate Nazi ideology. The foregoing quote helps illustrate Barth's cause for alarm.