The only reality in the world, or so it seems, is that there are three natures of truth. Most folks are oppressed, a few folks are oppressors, and many of us simply underwrite the status quo. Within this context, it my contention that A) there will never be world peace, and B) most Americans have little or no interest in a real world peace, because it would require a great deal of sacrifice on our part. This leads me to the role of the church, which, upon recognition that the world is oppressive, and full of violence all of the time, and reticent about suffering on behalf of others, needs a new game plan.
Oh, we should still try to change the world, or at least recognize that the world was changed drastically by the victory of God over the world's rejection of peace and justice through the resurrection, but we need to do it on Jesus' terms, and not the terms of the world that has accepted the reality that has been stated above. We need to live our lives as though the world has been changed.
It is the church's role to offer an alternative to the injustice and violence of the world by creating a lasting alternative to it, not by coercing the world into an existence that suits a morality that makes sense only to the People of God. Justice and peace are terms used by most Americans only when American interests are involved, and with little regard for how such hopes are achieved. Military might has generally failed to promote a lasting peace of any kind, unless you consider that the welcoming of defeated enemies into the domination system of western powers counts as justice. It's a tentative peace at best, held together by the fact that the US still dominates oil interests and remains the head puppeteer for most developing countries. Wait until Europe gets frustrated again. Well, except for France.
Anyway, back to the point. If we accept that there will never be world peace, then it should be the church's place to be a community separate from the world, yet insistent upon serving a world that rejects the truth of the resurrection because God commands us to relieve the suffering of those who are oppressed.
We cannot relieve suffering, however, by continuing to acquiesce to dictum of socialist nation states or the tenets of liberal democracies. We can only witness against oppression by refusing to benefit from it. They world might refuse to buy into our truth claims, but AC/DC said it best "Prophecy ain't no riddle man, to me it makes good good sense!" Actually, that's a paraphrase, but I don't think they will mind.