One of the peculiar sins of the twentieth century which we've developed to a very high level is the sin of credulity. It has been said that when human beings stop believing in God they believe in nothing. The truth is much worse: they believe in anything.
Notes from Wikiquote
The last two sentences paraphrase a comment by Émile Cammaerts on a story by G. K. Chesterton: "When people stop believing in God, they don’t believe in nothing — they believe in anything."