The document that split Western Christianity in two

Martin Luther was 33 years old and an Augustinian monk when he nailed his 95 Theses to the door of the Castle Church in Wittenberg on October 31, 1517. The door functioned as a public notice board. Posting a list of propositions for academic debate was a standard procedure. Luther expected a debate among scholars.

The theses focused primarily on the sale of indulgences, a practice by which the church offered remission of punishment for sin in exchange for money. Johann Tetzel, a Dominican friar, had been selling them with a slogan commonly paraphrased as: "As soon as the coin in the coffer rings, the soul from purgatory springs." Luther found this theologically indefensible and said so, in 95 numbered propositions.

What happened next surprised everyone, including Luther. The printing press had been in operation in Europe for about 60 years. Someone translated the theses from Latin into German and printed them. Within weeks they had spread across Germany. Within months they were circulating across Europe. Luther had accidentally produced one of the first viral documents in the history of media.

The church's response was to demand Luther recant. He refused. The debate escalated. In 1521 he was summoned before the Diet of Worms, an assembly convened by Emperor Charles V, and asked to withdraw his writings. His response, "Here I stand; I cannot do otherwise; God help me", is possibly the most famous sentence in the history of the Reformation, though historians debate the exact wording.

He was excommunicated and declared an outlaw. He was hidden by sympathetic German princes and spent the time translating the New Testament into German, the version of the Bible that shaped the German language for centuries. The church he had not intended to split became the Lutheran church, and the larger Protestant movement he had not intended to found eventually encompassed hundreds of denominations across the world.