A delusion that encourages belief where there is no evidence is asking for trouble. Disagreements between incompatible beliefs cannot be settled by reasoned argument because reasoned argument is drummed out of those trained in religion from the cradle. Instead, disagreements are settled by other means which, in extreme cases, inevitably become violent. Scientists disagree among themselves but they never fight over their disagreements. They argue about evidence or go out and seek new evidence. Much the same is true of philosophers, historians and literary critics.