Many factors lead to Barth’s radical break with liberal theology. Two, however, stand out as especially noteworthy. First, Barth found that liberal theology was useless in his weekly task of preaching the gospel to the people of Safenwil. As a result, he undertook a careful and painstaking study of the Scriptures and through it discovered “The Strange New World Within the Bible,” to employ the title of one of his earliest articles. In the Scriptures he found not human religion, not even the highest and best thoughts of pious people, but God’s Wod: “It’s not the right human thoughts about God which form the content of the Bible, but the right divine thoughts about men….”
The second factor that turned Barth away from liberal theology was an event. In August 1914 he read a published statement by ninety-three German Intellectuals supporting Kaiser Wilhelm’s war policy. Among them were nearly all of his theological teachers, whom he had until then religiously honored. Their support of the German imperialism led Barth to believe that something must be terribly wrong with their theology, if it could be so quickly compromised in the face of the ideology of war. Disillusioned by his teachers’ conduct, Barth concluded that he could no longer “accept their ethics and dogmatics, their Biblical exegesis, their interpretation of history.” For him the entire liberal theology of the nineteenth century had no future, and he turned his considerable but hitherto hidden theological talent toward its demolition.
During the war Barth began work on a commentary on Paul’s epistle to the Romans. Published in 1919, it unexpectedly created a furor because of its harsh criticism of liberal Protestant theology. According to one theologian of the time, Der Romerbrief (The Epistle to the Romans) fell like a bombshell on the playground of theologians. In it Barth affirmed the validity of both the historical-critical method of studying Scripture and the doctrine of verbal inspiration, and he stated that if he were forced to chose between the two, he would choose the latter. Barth criticized liberal theology for turning the gospel into a religious message that tells humans of their own divinity instead of recognizing it as the Word of God, a message that humans are incapable of anticipating or comprehending because it comes from God utterly distinct from them. In essence Barth was calling for a revolution in theological method….
–Stanley J. Grenz, Roger E. Olson, 20th-Century Theology: God and the World in a Transitional Age