The part that makes that position extremist in my view is the "God-given" bit, not anything that comes after. Because anyone can say "I have a God-given right to X" for any X and there is no way to challenge that. It is the built-in immunity to challenge that makes such a position extremist.

There's nothing in the definition you gave earlier to support this interpretation. All that is required is that it be an immoderate or uncompromising position.

But justification is part of one's position. If you hold your position because you believe it is grounded in the Word of God, then no evidence or argument is going to dissuade you.

A new interpretation of the word of God could. Cognitive dissonance is an equally large issue in my opinion.

Justification isn't really part of the position, it's how you arrived at it.