The Protestant Reformation began in 15th century Europe as a reaction against corrupt practices in the Catholic Church. Martin Luther protested the sale of indulgences in 1517 with his 95 Theses. This sparked the Reformation and divided Western Christianity between Protestant and Catholic denominations. Luther's theology emphasized salvation by faith alone rather than works. His refusal to recant at the Diet of Worms in 1521 had wide religious, political, and intellectual impacts that transformed Europe.