Hear the verbal protestations of all men: Nothing so certain as their religious tenets. Examine their lives: You will scarcely think that they repose the smallest confidence in them. The greatest and truest zeal gives us no security against hypocrisy: The most open impiety is attended with a secret dread and compunction. No theological absurdities so glaring that they have not, sometimes, been embraced by men of the greatest and most cultivated understanding. No religious precepts so rigorous that they have not been adopted by the most voluptuous and most abandoned of men.

Part XV - General corollary - The Natural History of Religion (1757)