In medieval Europe, the Roman Catholic Church was the most powerful church, and its power was formidable and far-reaching. Church leaders controlled almost all aspects of medieval life, and the Church served many functions that in today's society we would consider to be governmental functions, such as law making/enforcement, military leadership, and granting ownership of land. The Church even controlled the ruling parties; for example, a King would need the Pope's permission to get a divorce.
Ultimately, the vast majority of people were concerned with getting into heaven, and so the Church's power was derived from their perceived ability to control whether or not a person made it there. People spent significant time and effort to avoid being punished for their sins in purgatory.The Church sold indulgences, which were papers that absolved you of punishment for certain sins. Many people signed up to fight in the Crusades or went on pilgrimages to earn forgiveness for their sins.
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