What financial abuses did Martin Luther criticize in the Ninety-five Theses?

In his Ninety-five Theses, Martin Luther primarily criticized the Roman Catholic Church's sale of indulgences, which he viewed as a grave theological error and an abuse of power. While the Church maintained that indulgences provided a remission of the temporal penalty for sin, Luther condemned the practice of selling them for money, arguing that it misled the faithful into believing divine forgiveness could be purchased.12

Luther specifically targeted the financial exploitation of the poor to fund the lavish lifestyle of the papacy in Rome, including the construction of St. Peter’s Basilica. Furthermore, he challenged the underlying corruption of the system, which was exacerbated by secret agreements to divert proceeds to pay off massive debts incurred by church officials, such as the Archbishop of Mainz, who had borrowed heavily to pay the pope for his high ecclesiastical offices—a practice known as simony. Luther argued that if the pope truly possessed jurisdiction over purgatory, he should empty it out of love rather than for financial gain.1324