Dual Citizenship

I have been contemplating dual citizenship, that is the role of Christians as citizens of some or another particular nation while being simultaneously citizens of God's Kingdom. Some would argue that we are not dual citizens, that we are Kingdom citizens and aliens in a strange land. There is much scripture to back that up. Not the least of which is a call to be in the world but not of it, which is not a command, but an implied position (John 17:9-19) .

However, I would argue that being in it means recognizing that we exist within of a particular nation. I also don't think that scripture tells us that being in any one nation or supporting it is bad, so long as doing so does not conflict with the ideals of the Kingdom or better stated, the will of God. I believe that when the two come in conflict, Christians have to side with God. Otherwise, you have made the nation your god, and the real, live, actual God has previously expressed His opinions regarding idolatry.

Is there a scriptural reference that specifically says we are citizens of both? I think there is, but haven't found one. I don't mean text that say submit to human institutions or honor and respect Emperors or anything of that nature, like Romans 13 or 1 Peter 2, but am looking for something that specifically mentions being citizens of a nation and what that entails as a Christian.

I ask because there is a plethora of the other, scripture saying we are strangers, exiles, sojourners, aliens in a foreign land, etc. (Ephesians 2:19, Hebrews 11:13, 1 Peter 2:11)

In a recent Youtube video I watched, titled John Piper's heart in the 2008 elections, Piper says we are dual citizens, but I couldn't help wonder what he based that on.

Some other commentary I found on the subject comes from a pastor's blog, Mike's Musings and from a Jim Wallis&Friends/Sojourners Blog by Rich Nathan.

The word we translate as world throughout the New Testament is "kosmou" the same Greek root from which we get cosmos. In the NT, we read that Satan controls the "kosmou" ( John 12:31, 16:11 and 1 John 5:19) but that we are to be in the world (John 17:9-19) while conforming ourselves, and our minds, to that of Jesus Christ (Romans 12:2). So, where does this fit into our political context?

If you have thought about any of this, please post them.