Pacifism comes in various forms, but let us take the paradigm as our model which is the view that no one (or at least no Christian) should kill another human regardless of the circumstances. And let us understand violence as the OED's primary definition of "violence":
a. The exercise of physical force so as to inflict injury on, or cause damage to, persons or property; conduct characterized by this; treatment or usage tending to cause bodily injury or forcibly interfering with personal freedom.One point that is seldom addressed is the fact that pacifism and nonviolence are not coextensive. Neither of the following propositions are true by definition:
1. If pacifism were true, then no violence is permissible.
2. If no violence were permissible, then pacifism is true.
Start with number one. One tells us that if pacifism were true, then one should never perform a violent act. But it does not follow from the proposition that all killing is impermissible that one should never inflict injury upon someone else or damage property. Even if pacifism were true, it does not follow that it is impermissible for one to destroy weapons intended to be used for terror or that it is impermissible to injure a terrorist.
Turn to number two. Two tells us that pacifism follows from the impermissibility of violence. Yet this does not follow, for one could nonviolently kill another person by giving him an overdose of morphine. Euthanasia is a form of nonviolent killing (sometimes at the request of the one being killed).
So those who hold that Jesus teaches both pacifism and an ethics of nonviolence have not a singular but a dual task of proving both pacifism and an ethics of nonviolence, since the one does not necessarily follow from the other.