Where?

Chapter and verse, please. Where does it say that all illness is caused by demonic possession?

Of course, you are the same person who asserted, in an answer to another question, "A major part of the dogma of most religions is the killing of all non-believers."

I just went through the Catechism of the Catholic Church (my religion) and I found absolutely nothing in there saying that one of my duties as a Catholic was to kill anybody.

So, you have asserted that the Bible attributes all illnesses to demons — and you have asserted that killing nonbelievers is "a major part of the dogma of most religions."

No offense, my friend, but with the above two claims in mind, a person would have to be crazy to believe anything you say. And I’m being kind when I say that.
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Catholic