[2] In 1947, Fairweather went to New York City to attend the Union Theological Seminary, where he obtained his ThD in 1949,[2] and where he undertook doctoral studies under the supervision of Paul Tillich and Reinhold Niebuhr.
[citation needed] Upon the completion of his doctorate in 1949 he returned to Trinity College in Toronto to teach, and in 1964 became the Keble Professor of Divinity.
[citation needed] He had a strong focus on certain major theological thinkers in the tradition of the Western Church such as Augustine, Anselm, and Aquinas, but at the same time exhibited a lively interest in (and wrote about) many important figures in the history of Canadian Anglicanism, such as John Strachan, John Medley, Tully Kingdon, and Harold Hamilton.
[citation needed] For many years he was a member of the Faith and Order Commission of the World Council of Churches and a Patron of the Tantur Ecumenical Institute.
He was in addition an official Anglican observer at the Second Vatican Council as well as a participant in the Anglican-Roman Catholic International Commission, in connexion with which the Cross of St Augustine was conferred upon him in 1981 by the Archbishop of Canterbury (Robert Runcie).