[Forest Keeper]

I think the missionaries encounter problems from the RC's because by introducing the preeminence of Scripture the argument for exclusivity falls apart and a great deal of what they do comes into question.

Yes, I couldn't agree more. I see a big part of it being a matter of W(w)ho is in control and W(w)ho has the power. Men by nature will always seek power, control, and exclusivity. Men who actually have the (human) power will naturally feel threatened by anyone who comes in and says that it is truly God Who holds all the power. That would be unacceptable.