I know how difficult it is to avoid illusions; perhaps the hopes I have confessed to are of an illusory nature, too. But I hold fast to one distinction. Apart from the fact that no penalty is imposed for
not sharing them, my illusions are not, like religious ones, incapable of correction. They have not the character of a delusion.

If experience should show — not to me, but to others after me, who think as I do — that we have been mistaken, we will give up our expectations. Take my attempt for what it is. A
psychologist who does not deceive himself about the difficulty of finding one’s bearings in this world, makes an endeavour to assess the development of man, in the light of the small portion of knowledge he has gained through a study of the mental processes of individuals during their development from child to
adult.

In so doing, the idea forces itself upon him that religion is comparable to a childhood neurosis, and he is optimistic enough to suppose that mankind will surmount this neurotic phase, just as so many children grow out of their similar neurosis. These discoveries derived from individual psychology
may be insufficient, their application to the human race unjustified, and his optimism unfounded. I grant you all these uncertainties. But often one cannot refrain from saying what one thinks, and one excuses oneself on the ground that one is not giving it out for more than it is worth.

Source: The Future of an Illusion page 53