Okay, I'm trying to get this all straight:
The Koran is the divine word of God, who is perfect, and he wrote it. Except for when what He wrote are incredibly offensive, immoral, disgusting, hateful, etc., and then this is all down to human interpretation.
The Koran is as meaningful and relevant and not needing of change as it was hundreds and hundreds of years ago. Except for all the bits that are mindbogglingly appalling and hateful, which, apparently is all down to interpretation.
The Koran is written so perfectly that no human could have created it, and its words and meanings are totally clear, except for when they are offensive, etc., etc., which is, yes, you guessed it, down to interpretation.
We non-believers are only being offended because we can't make our minds hold two utterly opposing things true at the same time: that a holy book is perfect, righteous and needs not the tiniest bit of change, as its words are absolute truths AND yet is simultaneously none of those and is purely a matter of subjective interpretation.
This would be the mental illness factors I have discussed previously. The correct term for this sort of thinking is called 'splitting', I believe.