Martin Luther came to the belief that salvation is reached by grace alone, through faith alone, as a gift of God alone. He believed that the debt of sin is paid by the death and resurrection of Jesus Christ, in contrast to the Roman Catholic Church's teaching, which was that the debt of forgiven sin could be paid for through indulgences. Martin Luther's intent in writing his Ninety-Five Theses was to create academic debate among scholars in the hope of bringing reform to the Catholic Church.
In his Ninety-Five Theses, Martin Luther addresses what he believes to be of importance to the heart of God, and I'd like to address three of these.
43. Christians are to be taught that he who gives to the poor or lends to the needy does a better deed than he who buys indulgences.
In both the Old and New Testaments, the writers talk about how God desires those who are in a weak position in society be taken care of—the poor, the needy, orphans, and widows, for example. Therefore, Martin Luther is saying that indulgence money would be better spent helping those who are less fortunate than in buying forgiveness, which is the free gift of God. John, in the Gospel of Luke, says,
Produce fruit in keeping with repentance...“What should we do then?” the crowd asked. John answered, “Anyone who has two shirts should share with the one who has none, and anyone who has food should do the same” (Luke 3:8; 10–11).
Martin Luther believed that the Church was not only perverting the gospel but also misrepresenting its teachings regarding the "fruit" (evidence) of repentance. It was doing so to line its own coffers.
Thesis 45 stays with this same theme of spending money to help those less fortunate.
45. Christians are to be taught that he who sees a needy man and passes him by, yet gives his money for indulgences, does not buy papal indulgences but God's wrath.
This thesis is reminiscent of the parable of the good Samaritan, in Luke chapter 10, where a priest and a Levite (two holy men) pass by a severely injured man. One would think that these two holy men, who were leaders in the temple, would be the ones to show grace and mercy and offer help to this injured man. This is also a condemnation by Luther of the priests and leaders in the Catholic Church who accepted money, frequently from the poor, in exchange for forgiveness. In the parable, it was the Samaritan, the one thought by the Jews to be of a lower class, who stopped and helped the man in need. It would be shocking to those reading Luther's theses, as well as to the readers of Luke, to think of God's anger being directed at the church leaders (or anyone) who would not help a beggar or someone in need.
Finally, in thesis 55, Martin Luther laments the fact that the Roman Catholic Church is proclaiming a man-made doctrine over the good news of the gospel.
55. It is certainly the pope's sentiment that if indulgences, which are a very insignificant thing, are celebrated with one bell, one procession, and one ceremony, then the gospel, which is the very greatest thing, should be preached with a hundred bells, a hundred processions, a hundred ceremonies.
The very foundation of the Christian church is the Gospel, Jesus Christ; therefore, Luther asks, why is the Catholic Church not celebrating this with huge fanfare and reveling? Why would the Pope have a man-made perversion of the gospel being celebrated with such ceremony in the church?
Martin Luther was calling for the reformation of the corruptions in the Roman Catholic Church.