Why was it important for Martin Luther to reform the Catholic Church?

Martin Luther was a monk (as he referred to himself) who lived in Germany during the late fifteenth century and early sixteenth century. At this time in Western Europe, there was one Christian church, the "Catholic" church. "Catholic" is a word that refers to the concept of a universal Christian church, which at that time and place, it was. 

In the time between Jesus Christ's death and Martin Luther's birth, the Church had been through...

Martin Luther was a monk (as he referred to himself) who lived in Germany during the late fifteenth century and early sixteenth century. At this time in Western Europe, there was one Christian church, the "Catholic" church. "Catholic" is a word that refers to the concept of a universal Christian church, which at that time and place, it was. 

In the time between Jesus Christ's death and Martin Luther's birth, the Church had been through a number of stages that were shaped by certain kinds of realities. The fact was that most people were illiterate, which meant that their only access to the Bible (which was in either the original languages, Hebrew and Greek, or translated into Latin, which most people did not understand) was through priests. The very human priests, over time, succumbed to myriad political and financial pressures across the Medieval period and gradually offered interpretations of scripture that benefited the church at the expense of the parishioners and that could not be challenged by the laity because the laity had no access to the Bible. 

By the time Luther came along, the Church's construction of Christianity could not address the questions he had about the concept of salvation and he also became concerned with the fact that the Church was selling escape from Purgatory and entry into Heaven. Luther challenged this and other practices in his famous 99 Theses. He also was part of the movement to make the Bible available to ordinary people through translating it into his native German. 

Luther was profoundly anti-Semitic and it is hard to overestimate the damage his views on the matter did to the Jewish people of Europe for hundreds of ensuing years. His views on Jews, when compared with actual scripture, are just as absurd as the views of the Church he criticized. At the same time, he managed to challenge the Church and not be martyred. In so doing, the door was opened to the roots of the wide range of Protestant churches in existence today.