Throughout Scripture, various motifs are given to describe the Christian life, motifs that can help us understand the way we should act as those who are called by God to be on mission in the World but not to be conformed to it (John 17:14-19). A third motif that describes the Christian life in this world is the language of elect exiles. Christians throughout the New Testament are identified as exiles, aliens, or sojourners on the earth: they are exiles in two senses, citizens of a foreign kingdom and residents of a different land.
As citizens of a foreign kingdom, Christians are not completely at home in this world: they are always looking to the city from which they get their true citizenship (Heb. 11:10, 16). The ultimate allegiance of Christian is not to an earthly state: it is to the Kingdom of God and the heavenly Jerusalem—their true city (Rev. 21:9-27). Thus, though Christians are called to obey their earthly rulers, they do not owe them their ultimate allegiance. They are to honor those God has put in power (Rom. 13:1-7), to not cause offense (Matt. 17:25-27); yet their ultimate allegiance is to God (Mark 12:17). It is out of their freedom as servants of God that they are to submit to every human institution (1 Pet. 2:13-17). But, because they are citizens of a different city, Christians are called to be different than those of the earthly city: “let us go to [Jesus] outside the camp and bear the reproach he endured. 14For there we have no lasting city, but we seek the city that is to come” (Heb. 13:13-14).
Furthermore, Christians live as exiles in a foreign land: they have no home here; they are from a different land, the New Creation. Christians are new creatures in Christ, therefore they are not at home in the Old Creation: they are ambassadors of the coming world sent to minister in their old country, to demonstrate the newness of what is to come in the midst of the darkness of what is fading away (Rom. 6:4, Rom. 8:18-15; 2 Cor. 5:17-21; 1 Pet. 1:17, 2:10-17; 2 Pet. 3:11-13). Christians, then, are freed from earthly allegiance to become what is necessary for the sake of the Gospel (1 Cor. 9:19-23); they are not bound to a specific people, but share a citizenship that transcends ethnic and social-economic boundaries (1 Cor. 1:26-31, 12:13; Gal. 3:28-29, 5:6; Eph. 2:19; Col. 3:11). Giving a description of Christianity in a letter written to Diognetus, an unbeliever, an early Christian writer wrote that Christians “live in their own homelands, but as aliens: they participate in everything as citizens, but endure all things as strangers. Every foreign land is their homeland, and every homeland is foreign.” Christians are thus radically free to use the benefits of citizenship for the furthering of the kingdom, as Paul did (Acts 16:37, 21:39, 22:25-29), but also free from the constraints of allegiance to any earthly nation.
(adapted from the paper, “Appendix 2 – Christ and Culture“)