Islam is supposed to mean the initiate's submission to the will of God and also his surrender and obedience to His law. Whereas radical Islam takes elements of the Islamic religion itself, and under that color, commits atrocities that these adherents purport to believe to be the will of God, but this cannot be morally right. Radical Islam believes for the most part, that apostasy to Islam is worthy of death, further that those that are of a different religion or of a different culture, may too be worthy of death, additionally Radical Islam often makes it a point of policy to kill or maim even children and other innocents in the name of their terror, and finally that women of their own religion, of their own bloodline, should be effectively treated as captives within their own religion, dictated to by the structure of radical Islam.
While it is not unusual for religions or certain cabals of people to have their factions that are radical, or even terroristic in nature, it is wrong, morally wrong, and also against the rule of Law, for these people or factions of people to assert their "justice" against others. When confronted with this type of rogue behavior, there are myriad ways to deal with the issues than presented; in regards to radical Islam, the confrontation that is necessary should come from those that have the most to lose from the corruption and the bastardization of their religion, and that is Islam, itself.
It is common sense to understand that when something that is important to you, perhaps the very essence of your being is being dragged through the mud, and becoming something that you know that it is not, that a righteous stand must be made against those that besmirch it. It has been said that for evil to triumph, you need just have good to step aside. Islam cannot afford to have their religion hi-jacked by agents or States that do not represent what Islam should truly represent, so by doing little or nothing to prevent this corruption of a religion which has over 1.6 billion adherents, those that believe Islam to be a religion of faith, fasting, and charitable giving will instead believe that their religion is one of vengeance and horror, to which all can be subjected to its awesome avenging sword at any time.
Those of the Islamic faith should make it a point and an abiding principle that those that hide behind Islam to justify their evil actions against others should be publicly rebuked and treated as outcasts to the faith. Islam believes at its very foundation that there cannot be any other God, but God, so it should not be possible to have such widely divergent views of what God represents from so many different people who all claim to be of the same basic faith. For instance, Christianity itself has many sects that are not in accordance with all doctrines of their faith, but fundamentally all of those of Christian faith believe that as part of that faith one should "… love thy neighbor as thyself." Islam too believes that "A kind word and forgiveness is better than charity followed by injury…"
Physician, heal thyself.