The researchers, led by Jordan Grafman, used data gathered from Vietnam War veterans and compared levels of religious fundamentalism between 119 veterans who had lesions and 30 veterans who didn't.
Results from the study published in the journal Neuropsychologia, showed that regions in the brain that had suffered damage through injury or disease in the ventromedial prefrontal cortex were linked to higher levels of religious fundamentalism.
People with lesions in this part of the brain have reduced "cognitive flexibility", which scientists believe makes them less able to change their views.
Grafman told PsyPost: "The variation in the nature of religious beliefs are governed by specific brain areas in the anterior parts of the human brain and those brain areas are among the most recently evolved areas of the human brain."
While the scientists highlight the significance of the results of their test, they made clear that they are not stating religious people overall are mentally inflexible or that belief is caused by brain damage. They acknowledged that there are many cognitive processes involved in forming beliefs, which in turn determines the level of a person's conviction.
