The term 'private citizen' is an oxymoron.
This was part of our pastor's theme yesterday, probably the most political of his career with us. There is no such thing as a private citizen. To be a citizen is to be an active member of the social structure, to be someone who works to help others and participates fully in civil and social discourse. There is nothing private about it. Further, to be a Christian citizen means acting for the common good. He quoted Isaiah’s admonition to his readers: don’t just go to worship on Sunday. It means nothing. Go out into the world, feed the hungry, help the sick and dying, raise up the downtrodden – then you may come to worship and tell me about it.
To take Isaiah even further: don’t be putting the ten commandments on the courthouse wall and believing this makes you a Christian citizen.