Faith and Order, Life and Work, and Amsterdam 1948

The Council's roots lie in two separate ecumenical movements of the early twentieth century that had not yet merged when the First World War interrupted them. The Faith and Order movement, growing out of a proposal made at a 1910 world missionary conference in Edinburgh, sought agreement among churches on questions of doctrine and church order; the Life and Work movement, associated especially with the Swedish Lutheran Archbishop Nathan Soderblom, pursued practical cooperation on social and international questions while deliberately setting doctrinal disputes aside. Both movements held major conferences through the 1920s and 1930s and increasingly recognized that their work overlapped.

Plans to merge the two into a single World Council of Churches were already advanced by 1938, but the outbreak of the Second World War delayed the Council's formal founding for a decade. It was constituted at last at its first assembly, held in Amsterdam in August and September 1948, with 147 churches from 44 countries as founding members and the Dutch theologian Willem Visser 't Hooft as its first general secretary, a position he had effectively held in an unofficial capacity throughout the war years while coordinating ecumenical relief work from Geneva.