This decision [to pursue US citizenship] raises big questions for me: What does it mean to become an American? What does it mean to be an American? Is it possible to fulfill the responsibilities of American citizenship while retaining citizenship in Canada and South Africa, or must those citizenships be relinquished? What is the relationship between the duties of a citizen of the USA and the duties one has to all of humanity—that is, can one be both an American citizen and in some sense a cosmopolitan? And perhaps the biggest question of all: what is the relationship between being a citizen of the USA and being a citizen of the kingdom of God?
This is not the stuff one typically hears from those American Christians who speak too readily of "saving America" or of a supposed American exceptionalism. Yet I can easily resonate with Strauss's questions, given my highest allegiance to the kingdom of God coupled with my subordinate citizenships in two (and possibly as many as four) political communities.
My own view is that, in a federal system, one already owes overlapping and simultaneous political loyalties to municipality, province/state and federation. Moreover, in a complex differentiated society an ordinary person has multiple commitments to such pluriform communities as state, church institution, marriage, family and a variety of voluntary associations. If any one of these claims ultimacy, in effect it assumes an illegitimate godlike status. True, many states may stake such a claim to the citizen's ultimate allegiance, but the Christian's citizenship in these is always a tempered and limited allegiance subject to the higher loyalty to God's kingdom. The just state will recognize this and will refrain from asking more than it should from its citizenry.