Born in Belfast, Ireland, the son of a jeweler, Orr was converted around age nine under his mother’s influence. The deaths of his father and an older brother in 1922 plunged the family into financial hardship and forced him to leave school and work as a bakery clerk to help support them.
While still young, he felt a strong evangelistic call and, in the early 1930s, began preaching in Belfast, then throughout Britain and Europe. In 1937 he married Muriel Carlson in South Africa, and the couple continued together through decades of ministry travel.
During World War II he served as a chaplain with the United States Army Air Forces in the Pacific. After the war ended, he went to Oxford, where he earned his doctorate with a thesis on the 1859 evangelical revival in Britain, later published as a book.
From the mid-1960s he became a professor at Fuller Theological Seminary’s School of World Mission, teaching missiology with a focus on the history of revivals. There he trained generations of missiologists and researchers.
His method was to compare revivals across different continents, from the Americas to Asia and Africa, seeking what preceded and sustained them, especially movements of united prayer among believers. In 1974 he founded an annual conference in Oxford bringing together scholars of the subject.
Historians such as David Bebbington, a specialist in British evangelicalism, have noted that Orr was so focused on showing what revivals had in common that he set aside a more careful analysis of the differences between them, a recognized limitation of his historiographical approach.
He was a close advisor to Billy Graham from early in the evangelist’s ministry and a friend of Abraham Vereide, helping shape the prayer breakfast movement that spread through parliaments and governments.
He died in 1987 in Ridgecrest, North Carolina, a day after preaching at a conference. His research archive, now held at Wheaton College, continues to be consulted by those studying the history of evangelical revivals.
