Final answer:
The Roman Catholic Church faced corruption accusations, like selling indulgences, which led to Martin Luther's protest and the Protestant Reformation, changing Europe's religious structure.
Step-by-step explanation:
The Roman Catholic Church was seen as corrupt due to clerical immorality, selling indulgences, and abuse of power, prompting the Protestant Reformation. Martin Luther's 95 theses in 1517 criticized the Church's greed and sparked a religious and political upheaval across Europe.
With the advent of the Reformation, European rulers saw an opportunity to decrease the Pope's influence and reinforce their own sovereignty, leading to a mix of peaceful reforms and brutal conflicts. Internal efforts for reform did occur, but the spread of Protestantism continued, permanently altering Europe's religious landscape.