If we accept the position that to read the words of Koran 8:12 is to irresistibly act on them we fall into the error of determinism, meaning the words made Jihan John cut the heads off of his victims. If determinism is true then silverware causes obesity, guns cause murder and the words of 8:12 ultimately cause beheadings, making the humans through which deterministic forces work their helpless victims.
Solzhenitsyn identified Marxist Communists as Manichaean Gnostics, meaning they were determinists who saw themselves as the forces of good whose mission was to rid the world of the deterministic forces of evil. In their madness they fell upon and murdered in excess of 60,000,000 men, women, and children
Solzhenitsyn warned the West not to fall into determinism. But we have, despite that we know that though millions of Muslims have read 8:12 and millions of Americans use silverware and own guns, but neither cut necks, are obese or murder other people.
According to Scripture, the real ‘cause’ of beheadings is the human condition and a will turned toward evil making 8:12 a convenient excuse or license for the outworkings of a will turned toward evil.