While I'm not saying Islam hasn’t provided anything, I cannot disagree with the above. The simple fact is Islamic terrorism and extremism is not a perversion of Islamic/Koran teachings, it is the expression of them! It would be quite easy to find Koranic justification for pretty much any extremist ideology and action; it is after all the source of them.
Slip lists some good information, but how many of the contributions were the direct result of the religion itself, rather than the people? The question is not what Muslim people have brought to the world, but what Islam itself has brought to the world. Big difference.
Sir Isaac Newton was a Christian, but we do not say that the law of gravity or his other scientific achievements were things Christianity brought to the world do we.
Do you feel a politician needs to justify his or her political beliefs?
Do you feel a scientist or a doctor needs to justify and give evidence for their beliefs, opinions and research in their area of work?
Do you feel Osama bin Laden needs to justify his beliefs and actions?
Actions derive from beliefs (as demonstrated by bin Laden), hence beliefs ought to be justified. If they are not, it is perfectly rational and justified to reject them and call them what they are, unjustified. Why should religious beliefs and claims be exempt from this? We do, after all, apply this notion to pretty much all other areas in life. On what valid reason should we dignify unjustified beliefs/claims?