I'd reiterate that Americans believe that themselves.
http://www.pewresearch.org/fact-tank/2015/08/04/70-years-aft...
> [T]he share of Americans who believe the use of nuclear weapons was justified is now 56%, with 34% saying it was not.
You really don't see the difference?
Americans justify the use of nukes on the basis of the war being just. For example, if we'd nuked Japan because we thought sushi was an abomination, approval of our use of nukes would plummet. If we'd nuked Japan after the war, approval would plummet. If we killed Japaneese Americans rather than Japaneese, approval would plummet. This is why it's dishonest to equate approval of the wartime use of nukes to the approval of the suicide bombing of civilians on a subway. The foundational beliefs have no similarity.
Also, saying that a large percentage of muslims feel like they are in combat with their countrymen doesn't make it any better... if anything it just makes the survey data scarier.
From http://www.samharris.org/blog/item/sleepwalking-toward-armag...
> More British Muslims have joined the ranks of ISIS than have volunteered to serve in the British armed forces.
In my brief explorations, I found that Jews found shelter in the Muslim Spain in an era when Europe was in full force to get rid of the 'Jewish problem'. Fair share of the likes of Andrei Breivik and Dylann Roof are also in the present Muslim world, especially in this neo-colonial era.
So would ISIS. You really think they're all sitting around going "gee, we're assholes and this what we're doing is wrong and unjust, but let's keep going!"? They think they're fighting a just war of survival against a new wave of Christian crusaders.
Sure, it's wrong, but it's a belief genuinely held.