Hi,
I think part of the problem with the OT/NT is that, while I think the overwhelmlying majoritiy of it falls in line with the Catholic interpretation, you can if you want ti be willfull ignorant about it argue those interpretations are wrong. So know you get into a he said she said discussion. However, with the Koran, you can see actual indisputable error in the text. If this text is supposed to be the word of God then how can there be an error in it. For one indisputable example look at Sura 5:116-117.
It clearly teaches that Christians are wrong because they worship Mary as a God. I think part of the quote is, “Then God will say: 'Jesus son of Mary, did you ever say to mankind: 'Worship me and my mother as gods besides God…” Right here you have Mohammed (sp?) believing that Christians are worshipping Mary as if she were God and the rest of th text is Jesus confirming that she shouldn’t be worshipped as God. Now it is a fact that Christians do not worship Mary a God, nor have ever worshipped her as God. Therefore, you have indisputible proof that the Koran teaches error by saying this is what Christians do when that is utterly false. If this is false then really you cannot say the Koran is divinely inspired inerrant truth.
You cannot say you have indisputable proof about teaching error in the OT/NT, just what you want to say is error. So how can you trust a book as the inerrant word of God when it so clearly already demonstrates a large indisputable error?