Reformation Day: 4 facts to know about the other Oct. 31 holiday

2. Varied dates

While Luther's specific act that began the Reformation occurred on Oct. 31, 1517, celebrations commemorating the action were not always performed and the dates vary.

"Officially, Reformation Day has been commemorated since 1567. Exact dates for the holiday varied until after the 200th celebration in 1717 when Oct. 31 became the official date of celebration in Germany and later expanded internationally," noted the apologetics website Got Questions.

"Within the Lutheran tradition, Reformation Day is considered a lesser holiday and is officially named 'The Festival of the Reformation.' Most Lutheran churches (and others who celebrate this day) commemorate it on the Sunday prior to Oct. 31."