[Jack]

So what's the root of the philosophical disagreement?

Short answer: the difference between thinking one's opinion is divinely inspired and thus cannot be questioned as opposed to accepting one's opinion to be conditional, fluid and not absolute.

I think the root of the problem is human ego (for lack of a better term).

There's certainly an element of that. Couple it with a lofty opinion of ones self and a lack of humility, then wrap it all in a humorless self-image and you have intransigent opposition.