On October 31, 1517, an Augustinian monk named Martin Luther, long fearful for his own salvation, seemed to unleash tremendous personal hostility when he nailed his famous Ninety-five Theses to the door of the cathedral in Wittenburg, Germany. This single action has traditionally been viewed as the beginning of the Protestant Reformation. Before it ended, several new theologies were formulated by at least two generations of reformers, causing Christianity to fall into centuries of division.
The term sola fide (“faith alone”) is often associated with Luther. It was a belief that provided him a great deal of inner tranquility. Once, while meditating on Saint Paul’s Letter to the Romans, Luther came to the verse that states that “man is justified by faith apart from works of the law.”  Luther took this to mean that a person does not have the capability to work out his own salvation because of his sinful human nature. Instead, God gives his free gift of grace, which stimulates faith and leads to salvation. Luther rejected, it appears, the admonition of the Apostle James that faith without good works is dead,  preferring to concentrate only on that which gave him inner peace.
Luther also opposed the buying and selling of indulgences, a practice quite rampant in the western Europe of his day. The Church has always taught that an indulgence is a remission of the temporal punishment due to sin, and Luther correctly pointed out that such forgiveness cannot be purchased. The abuse of selling indulgences and the erroneous attitudes it created are well illustrated by the slogan of a preacher in Luther’s time: “Another soul to heaven springs when in the box a shilling rings.” 
While justification and indulgences are the issues for which Luther is best remembered, many more grievances comprised his Wittenburg list. Some two years after he had posted them, he confided in writing to a friend that the idea of the Pope as the anti-Christ, once repellent to him, now seemed to have more plausibility. Luther at first had no intention of beginning a new ecclesial body. As he meditated on Scripture, however, he began to think that the Church should return to the gospel in its purest form as he envisioned it, eliminating what he regarded as unnecessary liturgical ceremony, hierarchical structure, and the like:For Luther everything began from his fundamental experience … salvation comes [to human beings] from God through faith alone. God does everything and they do nothing. Good works do not make people good, but once people have been justified by God they do good works…. So Luther turned his back on everything in tradition which denied the preeminence of scripture and faith. He rejected what appeared to him as a means, a claim on the human side to deserve salvation: the cult of the saints, indulgences, religious vows, those sacraments which [he could not find] attested in the New Testament. Anything not explicitly set out in scripture was worthless. All that counted was the universal priesthood of the faithful. In 1520, the papal bull Exsurge formally condemned forty-one of Luther’s propositions, and he was given two months to submit to the authority of the Church. In December 1520, he publicly burned his copy of Exsurge, and excommunication followed one month later.
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