Those who work with the mentally ill are generally in agreement that persons suffering from that affliction often share three common characteristics.
For one thing, they tend to be obsessed with something.
For another, they often suffer from delusions of grandeur. The psychiatric wards house many a person who believes that they are Jesus, God, the Seventh Angel of Revelation, the granddaughter/grandson of the Russian princess Anastasia, or similar.
Also, most mentally ill people are also deeply religious.
That isn't to say all religious people are mentally ill. However, deep religiosity is a common characteristic of those who are mentally ill.
(I certainly have often enough observed all three characteristics at work. While working at a remote site in the tropics, I saw two work colleagues go insane in the space of two years - a condition often referred to in this part of the world as "Going Troppo", i.e. brought about by extreme work stress, plus the environmental stresses produced by the climate. One in particular exhibited all three of those traits).