“There’s no point in believing in things that exist.”

“But all them things exist," said Nanny Ogg. "That's no call to go around believing in them. It only encourages 'em.”

“I don't hold with paddlin' with the occult," said Granny firmly. "Once you start paddlin' with the occult you start believing in spirits, and when you start believing in spirits you start believing in demons, and then before you know where you are you're believing in gods. And then you're in trouble.""But all them things exist," said Nanny Ogg."That's no call to go around believing in them. It only encourages 'em.”

“Wizards don't believe in gods in the same way that most people don't find it necessary to believe in, say, tables. They know they're there, they know they're there for a purpose, they'd probably agree that they have a place in a well-organised universe, but they wouldn't see the point of believing, of going around saying "O great table, without whom we are as naught." Anyway, either the gods are there whether you believe in them or not, or exist only as a function of the belief, so either way you might as well ignore the whole business and, as it were, eat off your knees.”

“Most witches don’t believe in gods. They know that the gods exist, of course. They even deal with them occasionally. But they don’t believe in them. They know them too well. It would be like believing in the postman.”

“Some people believe that when you die, you cross the River of Death and have to pay the ferryman. People don’t seem to worry about that these days. Perhaps there’s a bridge now.”

“...either the gods are there whether you believe or not, or exist only as a function of the belief, so either way you might as well ignore the whole business...”