then there also is the "Sin" of omission. If you refrain from telling someone that the building is on fire, then I say you are guilty from withholding important information.
Now if your family was being held hostage by a terrorist or something and the only way to save them is to use your magic death powers, then that's a very interesting situation. I would have to say that I probably would use the death power at that point. That contradicts what I said before, but hey, I'm human. Humans are hypocritical and contradict themselves all the time.