The point is, it's possible for the same person to be rational about one thing, and irrational about another. In your case, the willingness to accept the health

The point is, it's possible for the same person to be rational about one thing, and irrational about another. In your case, the willingness to accept the health dangers of fireplaces cannot be used to meaningfully demonstrate that your belief in the supernatural must be rational. I think you're right though that irrationality is not necessarily rooted in emotion. There are probably multiple reasons why sometimes malicious memes thrive in brains and no single brain is immune to all of them. That's the price we pay for being cultural and communicative beings. Personally, I think fireplaces are nice, not as a heat source but recreationally. But I know it's irrational ;-)