Final answer:
Martin Luther challenged the Catholic Church due to the sale of indulgences, taxation, and the use of Latin in Mass, which led to the Protestant Reformation. He advocated for the Bible in vernacular language and salvation by faith alone, diverging from Catholic teachings. Luther's reforms became the foundation of Lutheranism after his ideas spread widely through the printing press.
Step-by-step explanation:
Martin Luther, a German monk, initiated what is known as the Protestant Reformation due to several critical issues he observed within the Catholic Church. His primary concerns involved the sale of indulgences, a practice where the Church sold certificates believed to reduce punishment for sins, taxation of the populace for the Church's gain, and the use of Latin in Mass, which was not understood by the general congregation. He found these practices contrary to Christian teachings and believed that they exploited believers for the Church's financial benefit.
Luther's other core arguments included advocating for the Bible to be published in common languages to be accessible to all people and promoting the doctrine that faith alone was sufficient for salvation, challenging the Church's teaching that salvation could be attained through purchases or good deeds. His posting of The Ninety-Five Theses in 1517 voiced his concerns and called for reform. Despite initially hoping to reform the Church from within, Luther's actions triggered a broader movement and ultimately led to the creation of a separate branch of Christianity known as Lutheranism.
Although the Catholic Church condemned Luther as a heretic, the advent of the printing press enabled his teachings to quickly spread throughout Europe, gaining a significant following and dramatically changing the religious landscape of the Western world.