Interpretations, you got it wrong

Ahh... Interpretations. One of the favorite defense by believers for their holy books.

"You have misinterpreted that phrase."

"That's not the true meaning of that line."

"It's supposed to mean metaphorically."

"God didn't mean it that way."

"You need to go for bible study lessons."

Hmm... I supposed that these (from the Bible) and these (from the Koran) were misinterpreted as well?

Here's some questions to think about:

Why suppose that the holy books require "special interpretation"?

What makes certain people so special such that they are "authorized" to interpret "correctly"?

What's the reason for god to allow his/her/its holy book to be open to so many "misinterpretations"?

Does the holy books have little footer notes that say "interpret this metaphorically" or "this one is literal"?

In particular, the large amounts of lines in the Koran that advocate death for unbelievers, are they literal or metaphorical? If metaphorical, metaphorical for what?