Confusion of the Kingdoms

Constitutional lawyer John Whitehead recently editorialized that Christians should be pacifists since Christ preached a message of non-retaliation and non-violence. He used as the model for Christian pacifism the sainted Martin Luther King Jr., the celebrated civil rights activist of hippie lore. This kind of drivel naturally drives confessional Lutherans, and others, up a wall. It is a horrible confusion of the two kingdoms.
Christians live in two kingdoms. The kingdom of the right is the Church, a dispenser of mercy and grace in the world through the Word and Sacraments. If he were referring to this kingdom he would be correct. The Church does not take up arms and settle worldly disputes. Jesus said, "My kingdom is not of this world." But the kingdom of the left is a kingdom of justice exercised by worldly power. It is a dispenser of vengeance and wrath wielded by the use of reason. It too is ruled by Christ since His ascension not by the Word but by human reason.
The problem with Whitehead's thesis is that he confuses the two kingdoms. Christians are citizens of both kingdoms. Christians are called to peace and mercy by the Church, but are called to arms and defense of justice by the State. As individuals living in the kingdom of the right we are indeed called to non-violence, but as citizens of the left hand kingdom we are called by legitimate authority to the defense of the nation. When rulers, who happen to be Christian, occupy an office in the left hand kingdom, they operate according to the callings of that office rather than their calling as Christians. This view is endorsed by Scripture in Romans 13.
Whitehead should stick to constitutional law and leave theology to the theologians.