Your argument assumes that ISIL is a religious group, rather than a terrorist group that uses religion as a prop.
But Timothy McVie who wasn't even a Christian did do it for religion, right?
You say that with such certainty:
McVeigh was raised
Roman Catholic.
[89] During his childhood, he and his father attended
Mass regularly.
[90] McVeigh was
confirmed at the Good Shepherd Church in Pendleton, New York, in 1985.
[91] In a 1996 interview, McVeigh professed belief in "a God", although he said he had "sort of lost touch with" Catholicism and "I never really picked it up, however I do maintain core beliefs."
[89] In McVeigh's 2002 biography
American Terrorist, he stated that he did not believe in
Hell and that science is his religion.
[92][93] In June 2001, a day before the execution, McVeigh wrote a letter to the
Buffalo News identifying himself as
agnostic.
[3] Before his execution, McVeigh took the Catholic sacrament of the
Anointing of the Sick.
[94][95][96][97][98]