In this encounter of Jesus, with the Pharisees in Matthew 22, he is questioned about taxes.  In response Jesus points out that there is the Kingdom of this world and the kingdom of God.  As Christians we have a dual citizenship characterised by duty to the one a devotion to the other. Jan points out John 15:18-19 which tells us that in Christ we are no longer part of the world, and in Romans 12 that we are to give our bodies as living sacrifices – not copying the world but being transformed in it.