Because he has to be right all the time.

If he isn't right about Iodine 100% of the time it registers as a personal attack in his brain.

Narcissists share this trait although he is probably not a full blown narcissist. But then again you never know with all of that bible crap.

Speaking of which it's ok to question everything about everything in the media, but a piece of fiction written 2000 years ago and edited 1000 times, no, that one you have to take at face value.