Religion as a mental illness

[Cephus]

But that really is the problem, isn't it?  The determination is entirely subjective, something that we don't do with other medical diagnoses.  Either you have cancer or you don't.  What people in that particular area think about cancer is irrelevant.  How many people have cancer in that area is meaningless.  You either have it or  you don't. But psychological diagnoses are subjective.

Good point. You can diagnose a physical cause of a delusion and that will be objective. And in the vast majority of people, religion (or any other non-rational belief) has no physical cause as a result of a physiological malfunction but of the general limitations of our species.

But you ought to be able to say that a belief in anything that we cannot demonstrate to be real is, by definition, a delusion.  It doesn't matter whether you're talking to a giant invisible rabbit or a god, we have no reason to think that these things exist, thus they represent a mental aberration.  But the people who believe in Harvey get put away or drugged up, the people who talk to gods do not.  It's hypocritical.