But there are forces at work within Islam itself. Last year, an Iranian scholar stressed out that the surats of the Coran were written in two different cities : Medine, and La Mecque, and that the most violent ones addressed the political and theological situation that prevailed in Medine (IIRC) at that time.
The problem, as you said, is that present Islamic schools, especially in Third-World countries, preach violence and destruction of the infidel. But they could as easily preach the more tolerant messages you will also find in the Coran.
Ambiguous central messages? Does the Bible have a different central theme from the Sermon on the Mount????