一寸長くなりますがタイトルに使われている "delusion" について書かれている個所jを引用します。
The word 'delusion' in my title has disquieted some psychiatrists who regard it as a technical term, not to be bandied about. Three of them wrote to me to propose a special technical term for religious delusion: 'relusion'. Maybe it'll catch on. But for now I am going to stick with 'delusion', and I need to justify my use of it. The Penguin English Dictionary defines a delusion as 'a false belief or impression'. Surprisingly, the illustrative quotation the dictionary gives is from Phillip E. Johnson: 'Darwinism is the story of humanity's liberation from the delusion that its destiny is controlled by a power higher than itself.' Can that be the same Phillip E. Johnson who leads the creationist charge against Darwinism in America today? Indeed it is, and the quotation is, as we might guess, taken out of context. I hope the fact that I have stated as much will be noted, since the same courtesy has not been extended to me in numerous creationist quotations of my works, deliberately and misleadingly taken out of context. Whatever Johnson's own meaning, his sentence as it stands is one that I would be happy to endorse. The dictionary supplied with Microsoft Word defines a delusion as 'a persistent false belief held in the face of strong contradictory evidence, especially as a symptom of psychiatric disorder'. The first part captures religious faith perfectly. As to whether it is a symptom of a psychiatric disorder, I am inclined to follow Robert M. Pirsig, author of Zen and the Art of Motorcycle Maintenance, when he said, 'When one person suffers from a delusion, it is called insanity. When many people suffer from a delusion it is called Religion.'
著者のRichard Dawkinsは大胆に宗教は "delusion" と主張しています。
最後の文 "When many people suffer from a delusion it is called Religion." は至言だと思います。