The last 20 centuries of Christian history have witnessed the emergence of numerous theological traditions. Many of these traditions today have relatively minor significance, while others remain a vibrant part of contemporary religious culture. And while some theologians, such as Martin Luther, Thomas Aquinas, and John Calvin, are relatively well known, others have become more obscure. This reference provides alphabetically arranged entries for more than 450 Christian theologians from antiquity to the close of the twentieth century. Entries are restricted to theologians who died before 1994, when this project was begun. Included are profiles for the most important and representative theologians from the Catholic, Orthodox, and Protestant traditions, with special attention to theologians of the English-speaking world. The volume covers those individuals whose work was primarily in systematic and spiritual theology, or church historians whose work was chiefly theological. Whenever possible, each entry provides basic biographical information, a brief account of the person's education and career, and a summary of the individual's most important contributions to theology. The entries range in length from 250 to 2,000 words, depending on the significance of the theologian's work. Each entry closes with a bibliography of primary and secondary sources, while the volume concludes with a selected, general bibliography.