I am a baptist (small 'b'), with anabaptist tendencies. The foundations of many of my beliefs are from what I call, Resident Alien Theology.
This theology holds that as resident aliens in a foreign land (this world), Christians' relationships with Christ are still foremost and our actions are guided by HIS commands alone, the demands of this world notwithstanding.
"Dear friends, I urge you as aliens and strangers in this world to abstain from sinful desires which war against your souls." - 1 Peter 2:11
Paul tells the Church at Philipi that his citizenship is in Heaven, as opposed to the Roman Empire (a citizenship that carried clout in Rome).
But because we belong to God and God alone, we have a different calling from a world who does not know Jesus. We are to follow the commands of Christ alone, because we have nothing here on this earth to hold onto (cf. Matthew 5:3). Jesus said himself, that his kingdom is not of this world. So why are we so worried about the stuff in this world, instead of the souls in it?
As a resident alien, my actions are guided by Christ, not by what a temporary world throws at me (I'm still working on this one actually). I do not see war and peace in a political manner, but rather as a spiritual one and an eternal one.
War does not in anyway help a situation. If you win in, I helps you. If you loose it, it helps the other guy. But it has never helped a situation. Wars only lead to more wars, and more deaths.
Because of this, there is no political purpose of a temporary world that I can see that would justify a Christian taking another person's life. When we weigh what is eternal (souls) and what is not (politics), how can we even begin to justfy what I see as breaking a command of Christ? However, I also make a big distinction on the call of Christians and the ideals of a secular nation-state. I understand the need for a nation to protect itself. I understand that war maybe the only alternative for a nation to ensure its survival. But we are not called to ensure the survival of a secular nation state. We are called be Christ followers, at any and all cost. I understand a nation's need to strike back at terrorists, per se, but I cannot justify a CHRISTIAN doing so. Christians serve God, who calls us to peace. Our calling from God takes precedence, over a calling from a nation we are only making our temporary home. We are resident aliens after all.
Christians should NEVER advocate for war. Whether you are a pacifist, or you see war as a last resort, Christians should never be the ones pulling for people to go to war. Christians in America are confusing Americanism with Christianity. We pursue wealth and prosperity, while trying to follow a man called Jesus who says "if you want to follow me, give everything you have to the poor and come." And it just doesn't work. We pursue money, popularity, ideals like freedom, and YAHWEH. And it doesn't work. That's the problem John is addressing in Revelation. The churches of the Roman Empire are assimilating into the pagan culture, because it's just too hard to make it by being faithful to Christ alone.
I am obligated to obey the commands of my Lord, and when they include turning the other cheek and offering mercy, I must do that - despite how bad or hard this temporary world makes it. I must turn my left cheek if I'm hit on the right one, end of story. I can not judge any situation or war differently from another (for political or Just War reasons), I am called to make peace and offer mercy. (period) This is what I'm commanded to do.
I also make a big distinction between dying for and killing for. I would die to protect those I love, but I would not kill to do so. I am called to nonviolence, and that's all I can do.
So, basically put, Resident Alien Theology holds that because I do not belong to this world, but rather to Jesus, I am supposed to follow ONLY him. Therefore, his commands take priority. I cannot judge or weigh them (for practicality, etc.) against a world I cannot claim. They simply are, and so must I be.