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.  They depend on what others in the area consider normal.  They depend on a subjective determination of whether they're a danger to themselves of others.  If you live in an area where everyone believes in unicorns, you're not delusional because your delusions are commonplace.  That's utterly stupid. Society doesn't get to set the standards for reality.  Reality exists regardless of what society wants.  That really makes psychology a pretty pointless pursuit.

The point of clinical psychology is to relieve subjective distress or disability.  What causes distress or disability may indeed be relative, not only between societies but within them as well.  There are people who get along fine in society with 'strange beliefs' and people with similar beliefs for whom they are a great dysfunction.  The point of diagnosis of mental disorders is to group people who may respond to a specific treatment together, and it is the response to treatment which forms the basis of diagnosis.  While the vast majority of religious people may have delusional beliefs, the prevalence in society seems to indicate that it is a product of a normally functioning brain.  Treating a normally functioning brain generally has no effect because there is no deficit in the functioning of the brain.  Since treatment doesn't apply to the religious, and they don't suffer distress or disability, it would make no sense to group them as mentally ill.

But that makes no sense whatsoever.  "Normal" and "common" are not synonyms.  If you had a society where chopping off people's arms was commonplace, would you consider that to be normal?  Is it healthy behavior?  Or is that unhealthy?  If the point of psychology is to make everyone just like everyone else, without an objective baseline, then what use is it?