Is it true that a servant's sincerity, certainty, reliance on Allah, and belief in divine decree and destiny prevent him from psychological illnesses?

Mental illnesses, such as schizophrenia and obsessive-compulsive disorder, require treatment and consultation with specialized doctors. Seeking treatment does not contradict a servant's sincerity, strength of conviction, and belief in divine decree and destiny; rather, it is part of it. The affliction of prophets and righteous people with illness indicates that a servant's possession of noble qualities does not guarantee their well-being. A person may be afflicted with a mental illness without it being a disparagement of their faith.