[1] With the outbreak of World War I, Roberts joined with Henry Hodgkin and others to launch the Fellowship of Reconciliation and he served as its first secretary.
In New York City he joined Reinhold Niebuhr and Kirby Page on the editorial board of The World Tomorrow.
[2][3] In 1922, Roberts emigrated to Montreal where in 1926 he wrote The Christian and War, “the definitive Canadian pacificist statement of the period”.
[1] Soon afterwards he moved to Toronto where he established a new chapter of the Fellowship of Reconciliation at Sherbourne Street United Church.
In the early 1930s, Roberts drafted the United Church of Canada’s endorsement of the World Disarmament Conference.