Clemens Cavallin talks about – An Interwar Demonstration of the Postwar Problems of Ecumenism. Nathan Söderblom, the Archbishop of Uppsala in Sweden, was one of the main promoters of Christian ecumenism in the interwar period. This movement, stimulated by battling of missionaries over territories throughout the globe, and horror over the divisions of fellow-believers in the First World War, sought to avoid such problems and horrors in the future by means of reconciliation among different denominations. This was rejected by the Vatican in the interwar period. A study of the actual thought of Söderblom helps to indicate why the Papacy was not convinced of the value of the movement, since his religious ideas not only denigrate the importance of doctrine in general, but tend to build religious conviction upon feeling and will alone.