The Theses, the Door and the Date

Reformation Day, on 31 October, commemorates the act taken to mark the beginning of the Protestant Reformation: Martin Luther's Ninety-Five Theses against the sale of indulgences, dated 1517. The traditional image, Luther nailing the theses to the door of the Castle Church in Wittenberg, is itself debated by historians. The door served as the university's notice-board, so a posting would have been an ordinary academic act rather than a dramatic defiance; the earliest account of the nailing comes from Melanchthon after Luther's death, and some scholars hold that Luther sent the theses to his archbishop that day and that the public posting, if it happened, came later.

What is not in doubt is the date of the letter and the rapid, printing-driven spread of the theses across Germany. The day is a public holiday in several German states and a major observance in Lutheran churches, kept with the hymn "A mighty fortress is our God". Its coincidence with the eve of All Saints is not accidental in reverse: Luther chose the eve of a great feast when indulgence-preaching was at its height. The 2017 quincentenary was marked by notable Lutheran-Catholic acts of common commemoration, a measure of how far the day's tone has shifted from polemic.