Final answer:
Martin Luther opposed the selling of indulgences by the Catholic Church, which he viewed as a corrupt practice that sold forgiveness and contravened the principle of salvation by faith alone. His challenges to the Church's authority and practices were articulated in his Ninety-five Theses, leading to his excommunication and the start of the Protestant Reformation.
Step-by-step explanation:
Martin Luther's View on Indulgences
Martin Luther was a German monk and professor who vehemently opposed the Catholic Church's practice of selling indulgences. Luther was particularly disturbed by the sale of indulgences near Wittenberg by Johann Tetzel, which spurred him to write the Ninety-five Theses. He argued that indulgences undermined the true Christian doctrine of salvation by faith alone, as they encouraged people to believe that passage to heaven could be bought. Furthermore, Luther denounced the church's taxation of ordinary Germans for the construction of St. Peter's Basilica, which he saw as exploitation of the faith of the poor to fund an extravagant project.
In his theses, Luther challenged the idea that the pope had authority over purgatory and could distribute the merits of Jesus and the saints as indulgences. This notion, according to Luther, had no basis in the Bible. He believed that forgiveness of sins could only be granted by God, and salvation was a matter of divine grace, not something one could purchase. These views led to him being summoned by church authorities, condemned by Pope Leo X, and eventually excommunicated from the Catholic Church.
Despite his initial intent, which was merely to reform what he saw as corrupt practices, Luther's actions ultimately ignited a movement that led to the birth of Protestantism. His translations of religious texts into the vernacular made the scripture more accessible to the general populace and facilitated the spread of his ideas across Europe, greatly supported by the advent of the printing press.