Stanley Hauerwas is Gilbert T. Rowe Professor Emeritus of Divinity and Law at Duke University.
Pacifists always bear the burden of proof. They do so because, as attractive as nonviolence may be, most assume that pacifism just will not work.
You may want to keep a few pacifists around for reminding those burdened with running the world that what they sometimes have to do is a lesser evil, but pacifism simply cannot and should not be, even for Christians, a normative stance.
Nonviolence is assumed to be unworkable, or, to the extent it works at all, it does so only because it is parasitic on more determinative forms of order secured by violence. Those committed to nonviolence, in short, are not realistic.
In contrast to pacifism, it is often assumed that just war reflection is "realistic." It is by no means clear, however, if advocates of just war have provided an adequate account of what kind of conditions are necessary for just war to be a realistic alternative for the military policy of a nation.
Just war in the Christian tradition
In the Christian tradition, realism is often thought to have begun with Augustine's account of the two cities, hardened into doctrine with Luther's two kingdoms, and given its most distinctive formulation in the thought of Reinhold Niebuhr. Thus Augustine is often identified as the Christian theologian who set the stage for the development of just war reflection that enables Christians to use violence in a limited way to secure tolerable order.