In Leadership pastor and author John Ortberg writes:
Psychologist Milton Rokeach once wrote a book called The Three Christs of Ypsilanti. He described his attempts to treat three patients at a psychiatric hospital in Ypsilanti, Michigan, who suffered from delusions of grandeur. Each believed he was unique among humankind; he had been called to save the world; he was the messiah. They were full-blown cases of grandiosity, in its pure form.
Rokeach found it difficult to break through, to help the patients accept the truth about their identity. So he decided to put the three into a little community, to see if rubbing against people who also claimed to be the messiah might dent their delusion. A kind of messianic, 12-step recovery group.
This led to some interesting conversations. One would claim, “I’m the messiah, the Son of God. I was sent here to save the earth.”
“How do you know?” Rokeach would ask.
“God told me.”
One of the other patients would counter, “I never told you any such thing.”
Every once in a while, one got a glimmer of reality—never deep or for long. Deeply ingrained was the messiah complex. But what progress Rokeach made was pretty much made by putting them together. — 750 Engaging Illustrations.