In For Whom the Bell Tolls , Ernest Hemingway writes of “that so mutable substitute for the apostles’ creed, the party line.” This observation reminds me of the quotation that Hayek chose as an epigram for Chapter II (“The Great Utopia”) of The Road to Serfdom. It’s by F. Hoelderlin , who wrote “what has always made the state a hell on earth has been precisely that man has tried to make it his heaven.”
Milan Kundera  issued the same warning many years later when, in an interview by Philip Roth, he remarked about Stalinism that “hell is already contained in the dream of paradise and if we wish to understand the essence of hell we must examine the essence of the paradise from which it originated.”
This, then, is my candidate for the most dangerous idea of modern times: the deification of the state. By this I mean the widespread belief that a particular set of people who proclaim a selfless love of humanity and who follow prescribed rituals that take place in official temples (usually made of marble) can achieve whatever is asked of them by the laity — if only the priests aren’t corrupt and the laity have sufficient faith and tithe generously.