Ronald Arbuthnott Knox was born in Leicestershire, England into an Anglican family (his father was Edmund Arbuthnott Knox who became bishop of Manchester), and was educated at Eton College and Balliol College, Oxford. In 1910, he became a fellow of Trinity College, Oxford. He was ordained as an Anglican priest in 1912, and was appointed chaplain of Trinity, but left in 1917 when he was received as a Roman Catholic. He explained his spiritual journey in two privately printed books, Apologia (1917), and A Spiritual Aeneid (1918). In 1918 he was ordained a Roman Catholic priest; in 1919 he joined the staff of St Edmund's College, Ware, Hertfordshire, remaining there until 1926.
He wrote and broadcast on Christianity and other subjects. While a Roman Catholic chaplain at the University of Oxford (1926-1939) and as domestic prelate to the Pope 1936, he wrote classic detective stories. In 1929 he codified the rules for detective stories into a 'Decalogue' of ten commandments.
Monsignor Knox singlehandedly translated the St. Jerome Latin Vulgate Bible into English. His works on religious themes include: Some Loose Stones (1913), Reunion All Round (1914), The Spiritual Aeneid (1918), The Belief of Catholics (1927), Caliban in Grub Street (1930), Heaven and Charing Cross (1935), Let Dons Delight (1939), and Captive Flames (1940). Monsignor Knox's Roman Catholicism caused his father to cut him out of his will. See Fitzgerald, The Knox Brothers (1977) at p. 261. This did not make much difference to his finances, however, as Knox earned a good income from his detective novels.
An essay in Knox's Essays in Satire (1928), "Studies in the Literature of Sherlock Holmes", was the first of the genre of mock-serious critical writings on Sherlock Holmes and mock-historical studies in which the existence of Holmes, Watson, et al. is assumed. Another of these essays (The Authorship of "In Memoriam") purports to prove that Tennyson's poem was actually written by Queen Victoria. Another satirical essay ("Reunion All Round") mocked the fabled Anglican tolerance in the form of an appeal to the Anglican Church to absorb everyone from Muslims to atheists, and even Catholics after murdering Irish children and banning Irish marriage and reproduction. Knox was led to the Catholic Church by the English writer G. K. Chesterton, before Chesterton himself became a Catholic. When Chesterton was received into Roman Catholic Church, he in turn was influenced by Knox. Knox delivered the homily for Chesterton's Requiem Mass in Westminster Cathedral.
In 1953 he visited the Oxfords in Zanzibar and the Actons in Rhodesia. It was on this trip that he began his translation of the Imitation of Christ and, upon his return to Mells, his translation of Thérèse de Lisieux's Autobiography of a Soul. He also began a work of apologetics intended to reach a wider than the student audience of his Belief of Catholics (1927). But all his activities were curtailed by his sudden and serious illness early in 1957. At the invitation of his old friend, Harold Macmillan, he stayed at 10 Downing Street while in London to consult a specialist. The doctor confirmed the diagnosis of incurable cancer.
He died on August 24, 1957 and his body was brought to Westminster Cathedral. Bishop Craven said the requiem at which Father Martin D'Arcy, a Jesuit, preached the panegyric. Knox was buried in the churchyard of St Andrew's Church, Mells.