Martin Luther was a German monk who sparked the Protestant Reformation through nailing his 95 Theses to a church door in 1517. This criticized the Catholic Church's practice of selling indulgences. Luther went on to translate the Bible into German and break from the Catholic Church by teaching salvation through faith alone rather than good works. He married and had children, translated the Bible, and wrote works establishing key Protestant doctrines like the two sacraments of baptism and communion. Luther's reforms transformed Christianity and established new Protestant traditions.