The link (below) is to a helpful post by Justin Taylor. In his introductory comments he presents Scriptural evidence for our dual citizenship, then concludes:
We are dual citizens, responsible and active members of both God’s spiritual kingdom and earthly kingdom. And if we seek to love the Lord our God with all our heart, soul, and strength—and to love our neighbor as ourselves—then we should care to some degree about politics and elections and the role of government in our land.
Then he unfolds two broad concerns: Some Christians “care too much” about politics, and some “care too little.” Very helpful stuff!