Nothing will convince them. The best way I can explain our previous moves on the world stage is that we had a "time machine" that allowed us to see what the world would be like if we let the other side have ctrl of resources. We did the best we could to stop that scenario from occurring under the constraints of American concepts of checks, balances, and a vague sense of "morality". The delusion Westerners share is symptomatic of the grossly excessive lifestyle they lead thanks to the "atrocities" they decry daily. This delusion is so strong it leads them to work against their own interests in an effort to gain favor with a God they don't even believe in. The beleaguered conscience of the overindulged average American will be the hand that ultimately leads them to the slaughter.
That "time machine" is algorithmic technology combined with vastly superior methods of espionage, which allows one to predict a country's policy decisions over a given period of time in accordance to their needs. It allows one to see into the future, and if a person possesses a particular lvl of intellect they can glimpse behind the veil of propaganda into the true past. Much like one can get a slight glimpse of the true intentions of Allied leaders in World War II by taking an honest look around them in 2015, and nothing is more honest than hard data on distribution of resources and real estate.
Imagine Arab conquerors making peace treaties based solely on trade interests with African nations during the so-called Dark Ages, and embedding Africans and Arabs among the cracker populations in Europe during that time. European advances in society would be closely monitored and guided by their rulers and when crackers had built a significant and efficient enough infrastructure throughout the "continent", the plan would come to fruition.
The order would go out for Arab and African armies to mobilize and slaughter most of the cracker ass cracker population in Europe, and leave the rest as slaves to be used by the ruling Arab and African class and traded to Asia for their own purposes. Asia would be allowed a predetermined share in African and Middle Eastern resources in exchange for total cooperation in the cracker slave trade. The world would clearly be a better place, and all it took were some grand "atrocities" by some men with vision of foresight and vastly superior knowledge to summon the courage to make the hard decisions.
People are being assassinated now because this is a Holy War being waged worldwide. Orthodox Islam is a religion of peace, but various hadiths turn it into a religion of conquest, subjugation, and death. Unfortunately, the followers of this b*stardization of Islam just happen to be sitting on the juice that makes the world go round, and they have their own ideas about how those resources should be divvied up. Ideas that could result in the subjugation and deaths of hundreds of millions of compassionate, spoiled, ignorant Westerners who live in a bubble insulated by layers of illusion. The people who are being whacked out must be hit, and collateral damage is a non issue due to the stakes of the game. Most of these kids hide behind moral indignation (hypocrisy, or laughable lack of self-awareness, really) to mask their lack of a feasible plan to get the enemy to come to the table and listen to reason and work against their own interests as they are so desperate to do themselves.