Which aspect of Church authority did Luther question?

Luther's challenge to Church authority primarily centered on the authority of the Pope. He argued that the Pope did not have the ultimate authority over matters of faith and salvation, emphasizing instead that scripture should be the sole authority (scripture alone) in religious matters. This reformist stance led him to critique the practices of the Catholic Church, including indulgences and the nature of the sacraments. While Luther did question certain sacraments, his fundamental argument revolved around the dismissal of papal authority, which constituted a pivotal point in the Reformation movement.

By advocating for a return to a more direct relationship with God through scripture, Luther asserted that individuals could interpret faith without the mediation of the Pope, fundamentally redefining the dynamics of religious authority in his time. This belief laid the groundwork for the Protestant Reformation and shifted the emphasis from institutional power to personal belief and interpretation.