Alfred Firmin Loisy (; 28 February 18571 June 1940) was a French Roman Catholic priest, professor and theologian generally credited as a founder of modernism in the Roman Catholic Church. He was a critic of traditional views of the interpretation of the Bible, and argued that biblical criticism could be helpful for a theological interpretation of Sacred Scripture. His theological positions brought him into conflict with the church's authorities, including Pope Leo XIII and Pope Pius X. In 1893, he was dismissed as a professor from the Institut Catholique de Paris. His books were condemned by the Roman Curia, and in 1908 he was excommunicated.