It’s hard to say what this is, but I know one thing for sure, Islam might not create killers, but killers are drawn to Islam. You see it time and time again, they are people who have problems, seek out Islam and then people die.
Only two things appear to turn people who are mentally weak or unstable to become homidical spree killers - Prozac (and other similar drugs) and Islam. You could argue whether people were already capable of being mass murderers and the drugs or Islam just pushed them over the edge. But there is no way to remove these two factors as being common denominators from every mass killing. Before Islam started killing in the U.S. in 1993, it was only psychotropic pharmaceuticals which caused unstable people to become murderers. Now, its a toss up.