Final answer:
Corruption in the Catholic Church prior to the Catholic Reformation was largely due to power struggles, simony, nepotism, and the lavish lifestyles of Church leaders, leading to the Protestant Reformation and the Church's subsequent internal reforms.
Step-by-step explanation:
Corruption in the Catholic Church prior to the Catholic Reformation was attributed to a number of factors including internal power struggles, the sale of church offices, nepotism, and the opulent lifestyle of the Church's hierarchy. For instance, the practice of simony, which is the selling of church offices, and nepotism, favoritism based on family relationships, were rampant and contributed significantly to the corrupt status of the Church. Moreover, popes and bishops often lived more like secular rulers than spiritual leaders, involving themselves in political alliances, commanding armies, and sometimes, waging war. These distractions from spiritual duties paved the way for criticism and ultimately led to calls for reform, such as those proposed by Martin Luther in the early 1500s.
Luther's calls for reform focused on the Church's greed and abuse of power and this led to widespread support for the Protestant Reformation. This movement challenged the Catholic Church's practices and doctrines, inducing significant religious, political, and social upheaval across Europe. The Catholic Reformation, or Counter-Reformation, saw the Church attempting to address these criticisms and reform from within, notably through the Council of Trent (1545) where steps were taken to curb clerical corruption and improve the education of the clergy.