Rationalism swept through Germany, more especially the illusion that man’s faculty could establish and secure a single, true, and salvation-guaranteeing religion. This rationalism expressed itself in pamphlets, in systems, in conversations, in secret societies and in many other institutions. It was not satisfied—indeed it did not even bother—to deny the distinctive doctrines of the Catholic church; its basis was rather the simple assertion: nothing in positive Christianity is acceptable except its “reasonable morality,” the doctrine that God is the father of all things, and the proposition that man’s soul is immortal; what goes beyond these three assertions is either poetry or superstition or pure nonsense.

Terry Melanson, Perfectibilists: The 18th Century Bavarian Order of the Illuminati [Amazon, Bookshop, Publisher, Local Library]