They were violent thugs who never intended for their demands to be met.
The term "violent thugs" doesn't really tell us much. Certainly common "thugs" don't go around making demands on other nations. Here is a statement from the kidnappers:
"A person whose identity was obscured then reads out in Urdu demands that "atrocities" against Muslims throughout the world cease, that Pakistani prisoners held at the US naval base in Guantanamo Bay, Cuba be released, and that the United States deliver to Pakistan F-16 fighter planes already paid for by Islamabad."
The last demand is somewhat obscure. The second seems to imply Pakistani interests. However, the first demand quite specifically points to an Muslim orientation. Based on the first statement or demand ("that atrocities against Muslims throughout the world cease") this group is quite clearly an Islamic terrorist group.
Was this group inspired by Islam to commit this atrocity? I don't know, but I have little doubt that the term "violent thugs" as a singular description is a distortion.
And when the KKK burns crosses and lynches Black people, that quite specifically points to a "Christian" orientation. Broad-brushing the entire membership of Christianity is absurd as is broad brushing the entire membership of "Islam" as "inspiring" of the acts of this particular group of people.