“There are some who are still weak in faith, who ought to be instructed, and who would gladly believe as we do. But their ignorance prevents them...we must bear patiently with these people and not use our liberty; since it brings to peril or harm to body or soul...but if we use our liberty unnecessarily, and deliberately cause offense to our neighbor, we drive away the very one who in time would come to our faith. Thus St. Paul circumcised Timothy (Acts 16:3) because simple minded Jews had taken offense; he thought: what harm can it do, since they are offended because of ignorance? But when, in Antioch, they insisted that he out and must circumcise Titus (Gal. 2:3) Paul withstood them all and to spite them refused to have Titus circumcised... He did the same when St. Peter...it happened in this way: when Peter was with the Gentiles he ate pork and sausages with them, but when the Jews came in, he abstained from this food and did not eat as he did before. Then the Gentiles who had become Christians though: Alas! we, too, must be like the Jews, eat no pork, and live according to the law of Moses. But when Paul learned that they were acting to the injury of evangelical freedom, he reproved Peter publicly and read him an apostolic lecture, saying: "If you, though a Jew, live like a Gentile, how can you compel the Gentiles to live like Jews?" (Gal. 2:14). Thus we, too, should order our lives and use our liberty at the proper time, so that Christian liberty may suffer no injury, and no offense be given to our weak brothers and sisters who are still without the knowledge of this liberty.”
Martin Luther changed the course of Western civilization by initiating the Protestant Reformation. As a priest and theology professor, he confronted indulgence salesmen with his 95 Theses in 1517. Luther strongly disputed their claim that freedom from God's punishment of sin could be purchased with money. His refusal to retract all of his writings at the demand of Pope Leo X in 1520 and the Holy Roman Emperor Charles V at the Diet of Worms meeting in 1521 resulted in his excommunication by the pope and condemnation as an outlaw by the emperor.
Luther taught that salvation is a free gift of God and received only by grace through faith in Jesus as redeemer from sin, not from good works. His theology challenged the authority of the pope of the Roman Catholic Church by teaching that the Bible is the only source of divinely revealed knowledge and opposed sacerdotalism by considering all baptized Christians to be a holy priesthood.
His translation of the Bible into the language of the people (instead of Latin) made it more accessible, causing a tremendous impact on the church and on German culture. It fostered the development of a standard version of the German language, added several principles to the art of translation, and influenced the translation into English of the King James Bible. His hymns inspired the development of singing in churches. His marriage to Katharina von Bora set a model for the practice of clerical marriage, allowing Protestant priests to marry.