“But a greater and wider evil arises when the credulous character is maintained and supported, when a habit of believing for unworthy reasons is fostered and made permanent.”

The Psychology of Religion (1927), p. 48.

Young India (21 May 1925)
1920s
Context: There is no principle worth the name if it is not wholly good. I swear by non-violence because I know that it alone conduces to the highest good of mankind, not merely in the next world, but in this also. I object to violence because, when it appears to do good, the good is only temporary, the evil it does is permanent.

Source: Dominion: The Power of Man, the Suffering of Animals, and the Call to Mercy

Plato, Phaedo

Mutual Aid: A Factor of Evolution (1902)

The Ethics of Belief (1877), The Duty of Inquiry
Context: A bad action is always bad at the time when it is done, no matter what happens afterwards. Every time we let ourselves believe for unworthy reasons, we weaken our powers of self-control, of doubting, of judicially and fairly weighing evidence. We all suffer severely enough from the maintenance and support of false beliefs and the fatally wrong actions which they lead to, and the evil born when one such belief is entertained is great and wide. But a greater and wider evil arises when the credulous character is maintained and supported, when a habit of believing for unworthy reasons is fostered and made permanent. If I steal money from any person, there may be no harm done from the mere transfer of possession; he may not feel the loss, or it may prevent him from using the money badly. But I cannot help doing this great wrong towards Man, that I make myself dishonest. What hurts society is not that it should lose its property, but that it should become a den of thieves, for then it must cease to be society. This is why we ought not to do evil, that good may come; for at any rate this great evil has come, that we have done evil and are made wicked thereby. In like manner, if I let myself believe anything on insufficient evidence, there may be no great harm done by the mere belief; it may be true after all, or I may never have occasion to exhibit it in outward acts. But I cannot help doing this great wrong towards Man, that I make myself credulous. The danger to society is not merely that it should believe wrong things, though that is great enough; but that it should become credulous, and lose the habit of testing things and inquiring into them; for then it must sink back into savagery.

The Ethics of Belief (1877), The Weight Of Authority

"No. But I stopped believing there was a power of good and a power of evil that were outside us. And I came to believe that good and evil are names for what people do, not for what they are. All we can say is that this is a good deed, because it helps someone, or that's an evil one, because it hurts them. People are too complicated to have simple labels."
Will and Mary in Ch. 33 : Marzipan
His Dark Materials, The Amber Spyglass (2000)

“Historical Legend and Revisionism?” 1980 lecture, reprinted in Forever in the Shadow of Hitler? New Jersey: Humanities Press, (1993), pp. 3-4.