This book argues that Christians should not put their hope in any sort of politician or political system but that Jesus really is the only Savior that we can truly put our hope in. Living like Jesus is the way we are political. Christian's started out as being anti-empire when Rome would have nothing to do with them. Everyone was forced to say "Caesar is lord," but this was the time that Christians took their lives into their hands and instead said, "Jesus is Lord!"
I think that so many times it seems that Christians think that voting a certain way is their Christian act or duty, but really our Christian act or duty has so much more to do with what we do ourselves as opposed to how we vote.
Our Christian act or duty is to help those in need, supporting them and helping them in the hard times. Our Christian act or duty is to show mercy to one another (a different kind of justice). Our Christian act or duty is to pursue justice for the oppressed. Not vote for someone who does these things, but do them ourselves. We put our hopes in Presidents and Kings, but God did not even want that kind of structure for his people, he wants us to see him as our president, and follow after him.
I think the next time I vote (which is generally every few months in Canada) I will write in who I really want to vote for...Jesus.