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.

 I disagree that all psych diagnoses are subjective. I left one category out, you can be mentally ill with delusions. The diagnosis in many of these cases is not that subjective, if subjective at all. Case example 1: An adolescent male (age 17) insists that he sees and rides dinosaurs and that they are in the room with you during the exam. No one on the staff can see them either. A hallucinatory delusion. Not very subjective when no one else can see the dinosaurs. Case example 2: An adult male (today's date) insists that he is Napoleon and can't understand why all people around him won't accept the truth. A delusion of grandeur. Given the time and place, not very subjective.

Your argument holds for the delusional but not necessarily mentally ill. Society is not setting the standard for reality, society is setting the standard for what belief/behavior is acceptable. Cross that acceptability line and the issue of mental health comes into play. That is subjective.

As far as psychiatry/psychology being a pointless pursuit, we can agree to disagree.

Which is really the same thing.  The only real worthwhile standard is accepting reality as it really is, not as you wish it was.  There either are gods or there are not gods. What society thinks on the matter is entirely irrelevant to what actually is true.  If people are not willing to accept what is true in the real world, or at least what is best supported, then what's the point?  We might as well be believing in magical unicorns and leprechauns.