Psychology 101

I posted it because I know such a person. Imagine a doctor of the mind, believing that demons can possess personal objects and the people who wear them counseling your kids! I would expect any qualified psychiatrist to have more rationality and be above superstitious nonsense in the 21st century. People who cannot distinguish between myth and reality (funda-mental-cases) should NOT be judging the "mental health" of others.

The meme reflects my personal experience with such hominids!

No-ones "reality" is based entirely on the observable. Even in psychiatry, it is permitted to believe the improbable. The problem is if you allow a belief to present itself as a harmful fixation or translate into harmful actions.
For instance, I believe in aliens, Bigfoot, the Loch Ness monster, fairies, and other "nonsense". I do not allow these beliefs to affect my life (I'm not wasting time hunting for proof that these things exist) and I can objectively say that maybe they don't.
If his beliefs cause him to behave in a harmful manner (such as treated recognized disorders as "possession" or to interpret a non-christians sessions through a Christian lens) then yes, it's a problem. If it is merely something he believes, but doesn't cause him to behave in an irrational manner, then let it go.

Also, some "mental issues" actually fixate more on the truth, than the non observable. If I consider myself a "failure" because I have (observably) failed relationships, below average income, and an unhealthy body, I could hate myself and be suicidal. That is a far bigger mental health issue than believing aliens exist, but they aren't affecting me.

There's nothing irrational about believing the Bible.

Do some personal research: Look up the treatment for leprosy.
Then look up the biblical cure for leprosy as written in the "perfect and infallible word of God".
Then look up the definition of "rational".

I think we disagree on the definition of "rational".

I sure hope we disagree on the definition of "rational."

There's no problem with God using one method to cure a disease at a certain time and place (e.g., ceremonial rituals performed by priests), and using another method at another time and place (e.g., medical treatments performed by doctors).

There's nothing about God's decision in that matter that which contradicts logic or reason. If another cure for leprosy is used in the future, would it mean that the treatments the doctors use today shouldn't have been performed? Of course not.