Martin Luther was born in 1483 in Eisleben, in Saxony, the son of a man who rose from mine work to own shares in copper smelters. His father wanted him to be a lawyer. In 1505, caught in a violent thunderstorm, the young student vowed to Saint Anne that he would become a monk, and he kept the vow. Luther joined the order of Augustinian friars at Erfurt, was ordained a priest, earned a doctorate in theology in 1512 and became a professor of the Bible at the small new university of Wittenberg.

A troubled conscience

Luther was an intensely scrupulous friar. He confessed for hours and still felt he could never love God enough to deserve mercy. Lecturing on the Psalms and on Paul's letter to the Romans, he came to read the phrase "the righteousness of God" in a new way: not as the standard by which God condemns sinners, but as a gift God gives them. This became the doctrine of justification by faith alone: sinners are made right with God by trusting his promise in Christ, not by earning it through works. Good works still mattered to Luther, but as the fruit of salvation, never its price. When exactly this breakthrough happened is debated, because Luther's own later account is hard to date.

The indulgence controversy

In 1515 Pope Leo X authorized an indulgence to fund the rebuilding of Saint Peter's Basilica in Rome. In parts of Germany it was preached by the Dominican friar Johann Tetzel on behalf of Albrecht of Brandenburg, archbishop of Mainz, who was to keep half the proceeds to repay loans from the Fugger banking house; he had borrowed to pay Rome for permission to hold more than one bishopric. What he saw was parishioners who thought a purchased letter freed them from the need to repent. On 31 October 1517 Luther sent his Ninety-five Theses, written in Latin as propositions for academic debate, to Archbishop Albrecht of Mainz. The famous story that he nailed them to the door of the castle church first appears after his death, in an account by his colleague Philip Melanchthon, and historians still dispute it. Either way, the theses were soon printed and spread across Germany.

From protest to break

At first Luther challenged abuses, not the papacy. Events pushed him further. At a debate in Leipzig in 1519, the theologian Johann Eck pressed Luther into admitting that church councils, as well as popes, could err, and that some views condemned in Jan Hus were Christian. In 1520 Luther published three treatises. In one, addressed to the German nobility, he argued for the priesthood of all believers: every baptized Christian shares the same spiritual standing, and clergy differ only in office. In another he cut the sacraments from seven to those he found instituted by Christ, chiefly baptism and the Lord's Supper. In a third, The Freedom of a Christian, he wrote: "A Christian man is the most free lord of all, and subject to none; a Christian man is the most dutiful servant of all, and subject to every one." Pope Leo X threatened excommunication; Luther burned the papal document in public, and in January 1521 he was excommunicated.

Worms

The young emperor Charles V, ruler of Spain, the Low Countries and the Austrian lands, summoned Luther to an imperial assembly, called a diet, at Worms. In April 1521 Luther refused to recant before Emperor Charles V at the Diet of Worms, saying his conscience was captive to the word of God and that to go against conscience was neither right nor safe. Early printed versions add the words "Here I stand, I can do no other," which he may not actually have said. The diet declared him an outlaw. His prince, Frederick the Wise, elector of Saxony, protected him, arranging a staged kidnapping that hid him in the Wartburg castle, where he began translating the New Testament into German.

The Catholic case

Catholic opponents were not simply defending corruption. Many agreed that indulgences were abused. Their objection was that Luther set his private reading of Scripture against the judgment of the whole church across fifteen centuries, and that "faith alone" seemed to undercut the call to holiness and love. Catholic teaching held, and holds, that salvation begins with grace no one can earn, but that grace transforms a person who then cooperates with it. Nearly five centuries later the gap narrowed: in 1999 the Lutheran World Federation and the Catholic Church signed a Joint Declaration on the Doctrine of Justification, stating a shared understanding of basic truths while noting remaining differences.

Worked example: two readings of the Theses

Thesis 27 mocks preachers who claim that a soul flies out of purgatory the moment a coin rings in the money chest. A Wittenberg student in 1517 might read this as a brave attack on greed. Tetzel's defenders could reply that official teaching said nothing of the kind, and that an obscure friar was undermining the church's power to console the grieving. Now notice what the Theses do not say: they still assume purgatory exists, and they still treat the pope as a shepherd misled by bad preachers. Reading a source for what it takes for granted, not only for what it attacks, shows how far Luther traveled between 1517 and 1521, and why neither he nor his opponents saw at the start where the quarrel would lead.