Is killing good or bad

It is wrong and is considered a form of homicide in most civilized countries. this is entirely different from passive neglect as the Batteries of Life are running down- and attempts to re-start are not done. Euthanasia may be legal in of all places, the Netherlands, but not elsewhere. There is some loose evidence that Mercy Killing in war situations ( in the middle ages) was practiced in the dark days of the Middle ages, but few specifics are known. This alone hints a barbarous custom akin to dueling.