개신교, or Protestantism, is a major branch of Christianity that originated in the 16th century during the Reformation. It emphasizes the authority of the Bible and the belief that salvation comes through faith in Jesus Christ alone. Key figures in the Reformation include 마르틴 루터 and 장 칼뱅, who challenged the practices of the Roman Catholic Church. Today, 개신교 encompasses a wide range of denominations, including 침례교, 감리교, and 장로교. Each denomination has its own beliefs and practices, but they all share a commitment to the core principles of faith, grace, and the importance of a personal relationship with God.