Uhm, because they're logical people?
Anyway, back to the main topic, uuuuuh... Yeah, don't trust that person. In my book, -anyone- who does therapy and does the slightest link with religion, no matter how well-intentioned, is in the wrong. Religion is one thing; life is another. Chances are that this therapist is going to try to cure you from your issue, which has been unilaterally demonstrated to be impossible.
I guess it's all right to go there once to please your wife and prove to her that there's no demon involved in this, but even if it rings true, I would seriously doubt each word that person says, simply because they are acting upon the false assumption that you are possessed.
Religious faith is a double-edged sword. It can give hope and (hopefully) teach good values, but it can also make the believer vulnerable to nonsensical statements and advice, as well as make them disbelieve facts (Earth is 6000 years old and dinosaurs are a test of faith according to some Protestants), oppose otherwise perfectly morally correct behaviours (homosexuality in Christianity, and even worse, in many factions of Islam) and amplify existing unhealthy political and moral conflicts, or even create them (Catholics vs Jews vs Muslims; political parties unhealthily using religion to validate invalid arguments...)
Sorry, I didn't mean to make this a religion debate. All I meant was that good will and a church's go-ahead are not sufficient qualifications for one to call themself a therapist, even though law sadly doesn't prohibit it. And even if that person actually has the right diploma, the use of religion in their practice is an unprofessional behaviour, actually illegal and passible of banishment from the profession, where I am.
Oh, and don't mention the holy spirit. Religious people see such a statement from someone they believe to be possessed as an actual proof of them having been tricked by one.
