Martin Luther

German Augustinian friar who initiated the Protestant Reformation by nailing the 95 Theses to the Wittenberg church door — developing the doctrines of justification by faith alone and the priesthood of all believers — and whose German Bible translation standardized the German language and made Scripture accessible to ordinary readers.

Broke the unity of Western Christendom — Luther's insistence on Scripture alone as authority and justification by faith alone removed the Church's monopoly on salvation and created the template for religious individualism that ultimately drove both religious freedom and modern subjectivism.