Spinoza wrote in the introduction to his book (A Theological-Political Treatise): "It is fear, then, that gives birth to superstition, preserves it, and strengthens it."

He says: There is no more effective way to govern the masses than superstitions; the reason that leads to superstitions, preserves them, and encourages them is fear... Freedom of thought does not pose a danger to faith; reason is the foundation of faith, for if it is absent, superstition appears, and if superstition spreads, reason is lost.