Angus was the eighth of nine children, born to a Scottish-immigrant father and his Nova Scotia-born wife. The family shared a small cabin surrounded by woods, where they farmed and fished in the rustic setting of the Bras d'or lakes. Gaelic was his first language, adding English when he first attended school. His final year in school was spent at North Sydney, where he lived in the home of Rev. T. Chalmers Jack. He was inspired to become a Presbyterian lay preacher, serving on horseback with cousin Duncan Archibald MacLean on the Saskatchewan prairies. With the outbreak of WWI, he became a medical orderly with the Canadian army, caring for the wounded at Halifax Harbor after the explosion of an ammunitions ship. He later served near the front lines in France. After the war he graduated from McGill University in 1920, where he also met his future wife. He prepared for the Presbyterian ministry at the Montreal Cooperative Theological College, where he was awarded a BD degree. He enrolled at Columbia University, earning an MA in 1924 and a PhD in 1930. By this time he had been appointed a professor of religious education at St. Lawrence University Theological School in Canton, NY, where he remained until retirement in 1960. He was then appointed minister of religious education at the First Unitarian Church of Cleveland in Shaker Heights, Ohio. Angus built a camp at Shin Pond in northern Maine, where he enjoyed the family get togethers, campfires, boating, and fishing. He was 5' 11" tall, with brown hair and blue eyes. He was skilled at woodcarving and oil painting. In 1945 he was ordained a Universalist minister, and was soon recognized as one of "the leading religious educators in the liberal religious movement." His theological and autobiographical writings constitute a lasting legacy.