Reddit mentions of The Three Christs of Ypsilanti (New York Review Classics)

The Three Christs of Ypsilanti is about an experiment where a psychologist gathers three paranoid schizophrenics who are each convinced they are Jesus Christ, to see how they resolve which of them really is.

Schizophrenia is a real brain condition, with documented abnormalities in regard to brain chemicals and brain structure. I would really encourage you to read some modern books or look up some journal articles on the subject. (If you're in college, your school likely has subscriptions to modern psych journals.)

In my experience, awareness doesn't necessarily help. I've heard that some people with schizophrenia can accept that some of their experiences are not real and learn how to respond accordingly. I think these people have probably had early interventions though. For my clients who are older and didn't have any intervention for decades--their beliefs are so fixed that it would basically be the same as me going up to a hard-core religious person and telling them that there is no God. They wouldn't believe me and I would lose all credibility in their minds. There's a book called "The Three Christs of Ypsilanti" where a doctor introduced three men who each believed they were Jesus to each other. The men all came up with reasons as to why the other two weren't Jesus, but they were.

The book about #9. Very interesting read!