Schizophrenia or demons?

One of my wife's sisters has been problematic recently. She had been a reasonably successful bank employee (not that I condone people becoming bankers) until she sank into depression after having to leave work due to being hit by a careless driver. It was then that her already troubled mind started to exhibit violent, erratic tendencies. Several family members think she may have schizophrenia, clinical depression, or some other mental ailment and should go see a doctor about it. This includes most of the siblings who are very religious; however, when praying for her, instead of talking about mental illness and seeking medical help, they ask God to protect her from the evil demons that are tormenting her mind. Ugh. What is it with these people? Can't tell the difference between mental illness and demon possession? It's downright embarrassing - they know that schizophrenia is a real mental condition yet it's confused in their heads so that they think this real condition is caused by demons poking at her brain. It's like we're living in some strange bastardization of the 21st and 14th centuries.