Psychiatrists are an absolute necessity. Prayer cannot rid a person of Bipolar Disorder or Paranoid Schizophrenia.
You have a problem of categories. A good place for you to start would be to take a more in-depth look at the entire concept of "mental illness" instead of taking it for granted as having an ontological reality, say, as a chicken or quartzite or helium has ontological reality. Start with
The Myth of Mental Illness and
The Manufacture of Madness by Thomas Szasz.