Final answer:
The Investiture Controversy significantly affected the Catholic Church's political power, challenging its authority and leading to a decline in its influence over state affairs. Subsequent events like the Great Schism and the Avignon Papacy further damaged the Church's authority and reputation.
Step-by-step explanation:
The conflict that resulted in the loss of political power for the Catholic Church is the Investiture Controversy. This power struggle between the Church and secular European monarchies during the 11th and 12th centuries significantly diminished the Church's influence over state matters. The Investiture Controversy centered around the right to invest bishops with the symbols of their office, which monarchs traditionally had a part in, but which Pope Gregory VII and his successors claimed exclusively for the papacy. This conflict challenged the balance of power and contributed to the decline of papal authority during the period.
Moreover, important historical events like the Great Schism and the Avignon Papacy also played pivotal roles in weakening the Church's grip on political power. The Great Schism, a period marked by divisions and multiple claimants to the papacy, further undermined the reputation and integrity of the Catholic Church. While the Investiture Controversy dealt a significant blow to the Church's temporal authority, later events like the Great Schism exacerbated the Church's declining influence in political matters.