William Laurence Sullivan (November 15, 1872—October 5, 1935) was an American Unitarian clergyman, prolific author and literary critic, whose Letters to His Holiness, Pope Pius X (1910), was the last work by a U.S. author to have been placed on Vatican's list of prohibited books (Index Librorum Prohibitorum). Early life and education A native of East Braintree, Massachusetts, Sullivan was born only a year after his parents, Patrick and Joanna (Desmon) Sullivan, had emigrated from the Irish town of Bandon in County Cork. The family subsequently moved to Quincy, Massachusetts. His father died when William was fourteen. He chose the confirmation name "Laurence" in honor of Lawrence of Rome, deacon and martyr. Intent on becoming a priest, he studied, between 1892 and 1896, at Boston College and St. John's Seminary in the Brighton section of Boston, where he took the degree of Ph.B. Career Catholic priest He joined the Paulist community at Catholic University of America in Washington, D.C. and received degrees of S.T.B. and S.T.L. He was ordained a priest in 1899. From 1899 to 1901 Sullivan served as a Paulist mission-preacher in Tennessee but returned to Washington due to poor health. He was assigned to parish work, teaching and writing for the Catholic Word. For several years he was Professor of Sacred Scripture and Theology at St. Thomas's College. He also contributed articles to the New York Sun and the New York Review, usually under a pseudonym. Under threat of dismissal for liberalism in his scripture courses, Sullivan requested to be relieved of his teaching duties and in 1908 was transferred back to parish ministry and mission work. In 1910 he resigned his pastorate in Austin, Texas, severed his ties with the Church, and wrote a polemic on papal authority, "Letters to His Holiness Pope Pius X". Unitarian minister In October 1910, while living in Cleveland, Sullivan affiliated with the American Unitarian Association. From 1911 to 1912 he taught English and history at Felix Adler's Ethical Culture School in New York. In 1912, he became a Unitarian minister, and served at All Souls Church in Schenectady, New York, moving, the following year, to New York City's All Souls Church in Manhattan, where he remained for the next nine years, until 1922. During this period he also spent six years as a book reviewer for one of the most prestigious of the city's many daily newspapers, The Herald Tribune.