" As regards pacifism, the belief that it is always wrong to kill a human being, again, anyone is free to hold this position, as immoral as it may be. And what other word than “immoral” can one use to describe forbidding the killing of someone who is in the process of murdering innocent men, women, and children, in, let’s say, a movie theater or a school? But it is dishonest to cite the commandment against murder to justify pacifism. There is moral killing—most obviously when done in self-defense against an aggressor—and there is immoral killing. And the word for that is murder. "

― Dennis Prager , The Ten Commandments: Still the Best Moral Code