You get right down to it, the muslim koran, the jewish koran, and the christian old testament are all alternate translations of the same stories.
Seems back in like 1800 BC or so (I don't remember how far back) a king (King David, as he's called in the modern christian translation) wanted to unite all the tribes under his rule. The best way to do that was by creating a common religon. So he had his scholars combine and adapt all the various stories and beliefs of all the tribes into one collection; the first "bible." Needless to say, the followers of that new religon split several times over history, new stories were added as time went on, and new translations and adaptions altered what was originaly written. The most obvious would be around 36 AD, when a handfull of jews split to form christianity, the followers of a guy who could of been the son of god or just a guy much like Ghandi, depending on what you believe. New stories, new writers, new adaptions, and new translations. Another is when King James had it translated to english, making sure that his right to the throne was protected in the translation. Yes, the bible that most christians follow today was written in a manner intended to protect the king of england.
My own studies here mostly covered the jewish stories, I was never able to dive much into the muslim adaptions before I shifted away from what I call the trillogy of same faiths, and began to study other beliefs that do not have their orgins rooted in Israel/Palestine.
Everything I've studied and read over the last 10 years, I've come to one conclusion: They all say to be good to one another, and nothing more needs be said. Problem is, this pisses off people who are devout fanatics of any part of the trillogy of same faiths. If people would judge a person by their actions instead of what they name their god(s), the world would be a lot better off. Why is it that you never see a bhuddist get pissed off because you say "no, I don't believe in your faith, but I share your main princible?"
Sigh...