Simon: Well they have this book ... called the Quran ...
Very well. The Quran exists, that is an "it".
How can we go from that "it" to what it means to be a good Muslim? (an "ought").
and then other books that chronicle Mohammed's life that it's adherents are meant to imitate.
There is the "ought". How did that follow? Did we just solve Humes problem?
Why are they meant to imitate it? Why can't they pick and choose like modern Christians/jews do, or organize their beliefs around a church hierarchy/tradition like the Catholics, or whatever?
Luke talks about a burning hell, IMO one of the morally corrosive ideas both found in the Quran and the Bible. Does that mean a person who does not believe in a burning hell is not a "good Christian"? I don't think so, I certainly don't think there are any logical reasons for it.