Alfred Firmin Loisy (1857-1940) was a French theologian, biblical scholar, and Roman Catholic priest. Loisy's six articles appearing in the Revue de clerge francais from 1898 to 1900 (under the name "A. Firmin") represent one of the earliest modernist attempts to develop a history of Christianity. His advocacy of a more liberal approach to the interpretation of Christian history and doctrine brought him into direct conflict with the Catholic Church. Loisy was removed from his position as professor at the Catholic Institute in Paris, his writings were denounced by the Vatican, and he was eventually excommunicated. This book will provide new translations of the five theoretical articles from the Revue de clerge francais, which form a theoretical introduction to Loisy's thought, and to the more historical concerns of his later writings. These five articles will be accompanied by a response by Loisy's contemporary (and frequent critic) Charles Maignen, as well as an introduction by the editor. The modernist writings translated here will be of interest not only to students of Catholic theology but also those interested in the liberal reforms of the turn of the century.