In October 1517, Martin Luther — a friar and professor of theology at Wittenberg — objected to the sale of indulgences, by which the faithful were told they could lessen the punishment for sin through payment. He wrote ninety-five theses, propositions for debate, and (tradition says) posted them on the door of the Castle Church.
Luther's intent was a scholarly disputation within the Church. But the theses, printed and spread quickly, struck a far deeper nerve. The questions he raised — about authority, grace, and the gospel itself — could not be contained, and Luther was eventually excommunicated.
From that spark came the Reformation: Lutheran, Reformed, Anglican, and later traditions, each described on its own page in the Theologos library. The reasons for the separation, in the reformers' own words, belong with those traditions; here the event is recorded as the turning point it became.
