Not to say that this is not bad, just saying that with ISIS homosexual killing does not seem like such a strange thing considering what they represent, and their hatred of Western Culture that tolerates and accepts this.
As for how they know well assuming they caught them in the act, if not its a witch hunt against people they don't like or go against them.
How can you say you're more concerned about artifact destruction or womens issues? Both are important but not more than a hunman life, especially the artifacts. You cannot compare killing homosexuals to destroying bits of fancy rock (as outrageous or immoral as it may be).
Well human historical history has a significant weight on our culture and in understanding what happened in the past it's value is debatable to a human life but the sheer amount of impact it can have on many lives puts it at number 1, women's issues well besides all the rape and murder going on over there and the chattel labor they die a slow death seems like a blessing in disguise to be killed immediately the inverse is tragic human suffering, with a miracle occurring in redemption.
It depends on where you put your general value at, for me the Homosexual killing is on a lower totem than the other two areas, but is still important after all its not nice to kill people, also ISIS is doing a lot of crazy things Homosexual murder is one that is consistent with their agenda, artifact destruction of other religions due to intolerance of false gods, and marital rape do fit in with their ideology but not as strongly as the former.
You can put it up as a value judgement which is more valuable ancient historical artifacts that can now never be appreciated by future generations but have been treasured and cultured for millennia by people all over the world and perhaps changed many individual lives for the better in countless ways, the suffering of people who are treated as slaves and are still living, or dead homosexuals or accused homosexuals in the country.
Tough call but I totem them up that way, some people will never decide or consider taking an action towards any of them.
Artifacts- Huge weight influences many people across generations when destroyed so are the positive externalities
Woman Issues - Long duration, suffering impacts many people, issue continues
Homo death - Death impact on a few individuals, society continues as it were until their is a change in the above two, either through a strong cultural and societal shift, or the living impacting the future.
So on a value of human life scale, one that impacts many lives versus one that impacts a few lives is the judgement weight.