This is based on Dr. Robert Sapolsky's wonderful lecture - Biological Underpinnings of Religiosity (   • Dr. Robert Sapolsky's lecture about B...  ).
Sapolsky is an amazing lecturer and neuroendocrinologist. In the lecture he dissects religion biologically and unbiasedly. Religiosity and the characteristics of religious people are identified with OCD & Temporal lobe epilepsy as well.

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References:
Adaptive advantage of schizophrenia (http://www.ncbi.nlm.nih.gov/pubmed/83...)
Adoptive, family and twin studies on relatives of schizophrenics (http://www.ncbi.nlm.nih.gov/pubmed/39...)
Schizotypal personality disorder (http://www.ncbi.nlm.nih.gov/pubmed/18...)
Psychopathology of shamanism (http://www.jstor.org/stable/3031794)