Final answer:
The condemned practice of buying and selling positions within the Catholic Church hierarchy is known as simony, which was notably banned by Pope Gregory VII during the Cluniac movement.
Step-by-step explanation:
The practice of buying and selling positions within the Catholic Church hierarchy was known as simony. This practice was condemned by many reformers, especially during the period of the Cluniac movement, which aimed to eliminate such corruption and restore spiritual integrity within the church. Pope Gregory VII in the 11th century notably banned simony and enforced clerical celibacy to prevent offices from being handed down as hereditary fiefs. Simony, along with other corrupt practices like nepotism, greatly contributed to the criticism of the Church, leading ultimately to reform movements such as the one initiated by Martin Luther in the early 1500s.