I think that the title is a bit misleading, because all religions are backward. Western societies are more liberal and progressive now than in the middle ages but that's not because we have different scriptures - the injunction to stone anyone working on the sabbath is still in our holy book - but it's because we have found ways to get around the awkward bits. Except of course when it serves our purpose not to ignore it, such as when we want to burn witches or condemn homosexuals - then the validity ofhe old scriptures is re-invoked!
But in the islamic world a narrow, fundamentalistic attitude to scripture developed centuries ago is still going strong, and (some would contend) only getting stronger, to the detriment of everbody (especially Muslims)
I have located what I think is an excellent article examing the historical and contemporary forces that have shaped islamic culture. I won't attempt to paraphrase it - I dont think it is over-long.