Pretty damned scary if you were a medieval Catholic priest
(A post I should ideally have done before midnight here but.....)
Today is not only Halloween, the time to celebrate all things eldritch and spooky, but also the 496th anniversary (so watch for the fun in four years' time) of Martin Luther's nailing of his 95 theses to the door of Wittenberg cathedral. Not only did this annoy the janitors (who must have heaved a sigh about vandalism to church property as they filled the holes), it started the Reformation. yes folks, five hundred years ago there were only two kinds of Christian: Catholic and Eastern Orthodox. Imagine that.
But seriously: Luther's ideas went on to bring Christianity to the common man, who would soon be able to read the Bible (or have his smarter kids read it to him) and find out about Jesus and his death and resurrection without the need for a guy in a frock "interpreting" it for him. Oh, and he brought in the idea that salvation wasn't something you earned from God by doing stuff (like, for example, giving money to the church) but something you got just by believing that Jesus was sent to save all of us poor sinners. Imagine that.
Like it or not, we all - Christian, Jew, atheist - live in Luther's world now. Even the Catholicism that dominates much of the world today has had to adapt in order not to be trampled underfoot in the revolution. You can keep your Marxes and your Darwins: Luther was the greatest revolutionary in human history.
Well, apart from Jesus. Obv.