Final answer:
Simon the Sorcerer, as mentioned in the New Testament, tried to buy the power of the Holy Spirit, an act that gave rise to the term simony. This buying or selling of church privileges was banned by Pope Gregory VII during the 11th century, a decision which altered the balance of power between the church and temporal rulers.
Step-by-step explanation:
The person who attempted to buy the power of the Holy Spirit was Simon the Sorcerer, as described in Acts 8:9-24 of the New Testament. Simon, after witnessing the apostles laying hands and conferring the Holy Spirit, offered them money to obtain this power for himself. This act is where the term simony, the buying or selling of ecclesiastical privileges or positions, originates.
Throughout history, the practice of simony became a significant issue within the church, prompting reform efforts to confront it. For instance, Pope Gregory VII banned the practice in the 11th century during the investiture controversy, which was a major struggle between the temporal rulers and the church for control over appointments to ecclesiastical offices.
In later centuries, challenges to ecclesiastical abuse of power would continue, prominently through figures such as Martin Luther. Luther's Ninety-five Theses were a seminal critique of the church's practices, including the selling of indulgences which he believed undermined the true repentance and forgiveness processes envisioned by Christian doctrine.