 1918 he became "Privatdozent" in University of Munich, from where he 1920 moved to theological faculty of the University of Marburg, where he became professor 1922.Dissatisfied with tridentine Roman Catholicism of his time he became Lutheran through the Evangelical Catholic influence of liberal Nathan Söderblom after meeting him in Sweden 1919 and receiving Holy Communion in Lutheran church.Soon he became directly involved with Lutheran High Church movement in Germany and 1929 became chairman of Hochkirchliche Vereinigung Augsburgischen Bekenntnisses.