You see, they are, without exception, psychologically disturbed individuals, with severe self-esteem and social-sexual issues. They WANT to kill, as does ANY psycho killer. Those he kills matter not at all, nor any "cause" surrounding the deaths. That is just convenient window dressing, useful at trial only.
These mutants, of course, are the same sorts who are very susceptible to the rantings of various zealots and jackleg preachers, who laud such animals in their sermons!
They are, in short, no different than the Al Quaeda, the PLO, Hamas, Islamic Jihad, IRA, or any OTHER terrorists...they use their "cause" for a mask...one which covers their underlying bloodlust with a thin coat of righteousness. Really, they JUST LIKE TO KILL.