Martin Luther occupies a place of major importance in the history of the Christian Church, the history of Europe and the history of religious thought. His significance derives in part from his youthful wrestling with a major theological problem. What that problem was, and how he resolved it, are of the greatest interest to historians and theologians alike. This book presents the most detailed examination in English to date of Luther's theological breakthrough, together with a wealth of information concerning the theological development of the young Luther in its late medieval context. Widely regarded as one of the most important works on Luther published in recent years, this paperback edition of Alister McGrath's classic text will be welcomed by students and scholars of both theology and history.