The Crucifixion Of Holy Saint Adolf by Adolf Wölfli (1864 - 1930)
The artist had a traumatic and violent childhood, and was committed to a mental asylum in his 20s, where he spent the rest of his life. It was during his incarceration that he started drawing, eventually producing over 1500 works and a 25,000 page illustrated 'biography' of Saint Adolf.
I wouldn't be that extreme, but I agree that it does not encourage rational thinking.
This being said, I know believers in various religions who are very good technicians, scientists or engineers. I have always wondered how it is possible to be so fact-based in your daily job and at the same time accept fantastic tales as the divine truth.
I know lots of people with serious mental problems, like schizophrenia, who have managed to keep themselves together with hard work and medication. They know the voices are fake…..