Scientific research like PET Scans and genetic analysis have proved that there's definitely a scientific basis for some if not all mental disorders (OCD, schizophrenia, etc.). I was just reading the effect of lithium and the size of certain parts of the brain. Manic-depressive people have smaller mass in 2-3 areas of the brain (that are associated with mood) than average people do. And some studies show that lithium treatment can help to increase the mass in those areas. The Religious angle is a mute point (as are other Religious perspectives, imo). It's not worth it to hold a debate about mental illness or other things with some groups of people.