It is absolutely evil, no ifs, ands, or buts. Notice that the terrorists have done something contrary to the innate ethical sense that they, possessing human genomes, most likely held at some prior time. Notice further that they have acted contrary to the innate, very powerful instinct for self-preservation. I believe not. I surmise that they expected to be translocated directly to a realm known as paradise where they believed their existence would continue.
Ideas can override innate behavioral programming that took millions of years to evolve.
What we are dealing with here is memes. A malevolent meme is a sort of computer virus of the mind, its human effect being the equivalent of the blue screen of death. A meme can act as a distorting lens through which to view the world, so that ordinary activities seem sinister and evil. War is peace, freedom is slavery, and love is hate, if you have the right meme. Biological systems are built ultimately on information, just as language is.