Lutheran refers to a branch of Christianity that originated from the teachings of Martin Luther, a German monk and theologian, in the 16th century. Luther's ideas challenged certain practices of the Roman Catholic Church, particularly the sale of indulgences, and emphasized salvation through faith alone, the authority of Scripture, and the priesthood of all believers. The Lutheran Church is characterized by its belief in the sacraments of baptism and communion, which are seen as means of grace. It has various denominations, including the Evangelical Lutheran Church in America (ELCA) and the Lutheran Church–Missouri Synod (LCMS), each with its own interpretations and practices.