It has long been my observation that anti-war Christian “pacifists” and pro-war Christian “realists” often talk past each other because they understand the church / state distinction very differently. Each labels the other dualist to the puzzlement of the other.
Here is my attempt to try and graphically illustrate the problem. Basically I think it’s a problem of space versus time. Of competing dualisms.
Realists tend to talk in terms of spacial relationships, of Heaven above and Earth below, of the “responsibility” to use state / military power wisely and the separate spheres of state and church influence. What is “of Christ” and “of Caesar” belong to different realms. Jesus is seen as denying a political role for himself, and any assertions to the contrary are absurd.
Pacifists, on the other hand, tend to talk in terms of the future Kingdom of God breaking into the present, with minimal respect for public life / private life and secular space / sacred space distinctions. Thus the crucifixion and resurrection are political as well as personal events, and “Jesus is Lord” is taken as a direct challenge to Caesar.
Having said that, I am aware this model may need some tweeking, so feel free to critique and suggest improvements where you feel it may be unclear. Does it help though?