The human person is a unique composite - a unity of spirit and matter, soul and body, fashioned in the image of God and destined to live forever. Every human life is sacred, because every human person is sacred.
I mean. . . if you're raised as a decent human being, killing somebody is against every moral thing you've ever been taught. And so, generally, in combat it's 'krauts,' the 'gooks,' the 'yanks' - whatever you want to do to try and make it so that it's not a human being.