from Wikipedia:  The Protestant Reformation

The Protestant Reformation was the 16th-century schism within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. It was sparked by the 1517 posting of Luther's Ninety-Five Theses. The efforts of the self-described "reformers", who objected to ("protested") the doctrines, rituals, and ecclesiastical structure of the Roman Catholic Church, led to the creation of new national Protestant churches. The Reformation was precipitated by earlier events within Europe, such as the Black Death and the Western Schism, which eroded people's faith in the Catholic Church and the Papacy that governed it. This, as well as many other factors, such as the mid 15th-century invention of the printing press, and the fall of the Eastern Roman Empire, contributed to the creation of Protestantism.

Martin Luther
Luther taught that salvation is not earned by good deeds but received only as a free gift of God's grace through faith in Jesus Christ as redeemer from sin. His theology challenged the authority of the Pope of the Roman Catholic Church by teaching that the Bible is the only source of divinelyrevealed knowledge[2] and opposed sacerdotalism by considering all baptized Christians to be a holy priesthood.[3] Those who identify with Luther's teachings are called Lutherans.

"Luther" The Movie - see trailer

Martin Luther : Reluctant Revolutionary

PBS documentary on Martin Luther (55 minutes)

Martin Luther ("Manic Monday" by the Bangles) on YouTube by the HistoryTeachers.