Delusion

When one person suffers from a delusion, it is called insanity. When many people suffer from a delusion, it is called religion.

A delusion is a false belief about external reality that is evidently false or that remains unchanged despite obvious evidence to the contrary. It is commonly (but not exclusively) the result of a mental disorder, such as schizophrenia or psychosis. Delusions are often bizarre, meaning physically impossible.

Systematically shared beliefs between close social groups, such as religious systems, are commonly regarded as delusions amongst scientists, philosophers, and psychologists, but are typically considered exempt by most clinical diagnostic criteria (e.g., the Diagnostic and Statistical Manual of Mental Disorders states that the belief must not be accepted by the person's culture or subculture). The noted New Atheist, Richard Dawkins, wrote a book entitled The God Delusion, in which he asserted that the question of God's existence was tied to the question of special creation, and then argued that since special creation has largely been demonstrated to be false, belief in God is a delusion.