Matthew 28:18-20 (ESV)
"And Jesus came and said to them, 'All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.'"
My pastor (Steve Kopp) preached on this today, spending the bulk of his time reviewing the core values of our church related to the imperatives of the Great Commission: to make disciples, baptize, teach, and obey. I love my church!
As he preached I began to see something in the passage I hadn't caught before. I was struck by the implications of 'make disciples of all nations' and what that would mean in its original political climate and also ours. It seems to me the Kingdom of God doesn't only cross national allegiances, at some level it must usurp them!
For example, my nation may ask me as a citizen to fight its wars against other nations. However, the Great Commission demands that I make disciples of all nations. This is a critical impasse of allegiances. How could I as a Christian, in good conscience, fight a war against those I am command by Christ to make disciples of? And yet this is exactly what a majority of Christians have done since Constantine...

This isn't to say the Church has to create its own military or political reality. By definition it is a political reality, but it is one very different than the world has ever seen! Christians don't... shouldn't... conquer by dominion or violence, but by loving our enemies and sharing the gospel of Jesus Christ! It's so radically different that it's easy to miss for those of us suckered into the world’s way of doing things. When the nations demand we kill for whatever paradigms of justice they've erected to justify violence we must resist! We must resist standing by the truth in love, inviting all nations to the table of Christ! Then we shall be known as peacemakers instead of stooges of the state.
Christians, remove the blinders we've allowed to slip over our gospel! Our political allegiance is first and foremost to the Kingdom of God and the teaching/ways of King Jesus! 

Matthew 20:25-28 (ESV)
"But Jesus called them to him and said, 'You know that the rulers of the Gentiles lord it over them, and their great ones exercise authority over them.
 It shall not be so among you. But whoever would be great among you must be your servant, and whoever would be first among you must be your slave, even as the Son of Man came not to be served but to serve, and to give his life as a ransom for many.'"
2 Corinthians 10:3-6 (ESV)
"Though we walk in the flesh, we are not waging war according to the flesh. For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. 
We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ, being ready to punish every disobedience, when your obedience is complete."