“Posting of Luther’s 95 Theses” by Julius Hubner, 1878. Historians debate whether Luther nailed his theses on the Church door October 31, 1517. Certainly he mailed a letter with a copy of the theses to the Archbishop of Mainz on that date. Probably the theses were posted on the church door, frequently used as a bulletin board for such calls to debate, in November of that year.