In Roman Catholicism , the remission of temporal punishment for a sin after the sin has been forgiven through the sacrament of penance.
The theology of indulgences is based on the concept that, even though the sin and its eternal punishment are forgiven through penance, divine justice demands that the sinner pay for the crime either in this life or in purgatory . The first indulgences were intended to shorten times of penance by substituting periods of fasting , private prayers, almsgiving, and monetary payments that were to be used for religious purposes. Pope Urban II granted the first plenary, or absolute, indulgence to participants in the First Crusade , and subsequent popes offered indulgences on the occasion of the later Crusades. After the 12th century they were more widely used, and abuses became common as indulgences were put up for sale to earn money for the church or to enrich unscrupulous clerics. Martin Luther 's Ninety-five Theses (1517) were in part a protest against indulgences. In 1562 the Council of {{link=Trent, Council of">Trent put an end to the abuses but not to the doctrine itself.