“No Erewhonian believes that the world is as black as it has been here painted, but it is one of their peculiarities that they very often do not believe or mean things which they profess to regard as indisputable.”

The Controller, Mustapha Mond, in Ch. 17
Variant: People believe in God because they've been conditioned to believe in God.
Source: Brave New World (1932)

Source: 1965 - 1995, Bravura', Per Kirkeby, (1982), chapter 'Klee and the Vikings', p. 83

Source: undated quotes, The Daily Practice of Painting, Writings (1962-1993), p. 78

Preface
1920s, The Practice and Theory of Bolshevism (1920)

"Professions for Women"
The Death of the Moth and Other Essays (1942)

Journal entry (8 July 1916), p. 74e
1910s, Notebooks 1914-1916

Psychedelic Society (1984)
Context: What blinds us, or what makes historical progress very difficult, is our lack of awareness of our ignorance. And [I think] that beliefs should be put aside, and that a psychedelic society would abandon belief systems [in favor of] direct experience and this is, I think much, of the problem of the modern dilemma, is that direct experience has been discounted and in its place all kind of belief systems have been erected... If you believe something, you're automatically precluded from believing in the opposite, which means that a degree of your human freedom has been forfeited in the act of this belief.

Source: 1970s-1980s, The Limits Of Organization (1974), Chapter 2, Organization And Information, p. 34