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 but not to be conformed to the World (John 17:14-19). A second motif given in Scripture is the identity of Christians within the Kingdom of God: they are described (among other things) as priests, soldiers, and servants.
First, as priests, Christians present to God spiritual sacrifices—their own lives and labours—and proclaim to the World the excellencies of the God who saved them (1 Pet. 2:5, 9; Rom. 12:1; Heb. 13:15; Rev. 1:6, 5:10).
Second, Paul encourages Timothy as soldier (2 Tim. 2:3-3) and gives instruction to him so that he might “wage the good warfare” (1:18). He speaks of Epaphroditus and Arichippus as his “fellow soldiers” (Phil. 2:25; Phlm 2), describing the Christian ministry as warfare against ideas raised against Christ, a warfare waged with divine power (2 Cor. 10:4). This idea of Christianity as warfare and Christians as soldiers in Christ’s Kingdom is applied to all believers in Eph. 6:10-20, where Paul describes the Christian life as a struggle with spiritual powers of darkness, fought by taking up the spiritual armor that God provides. Therefore Christians are engaged in warfare in this world, against ideas and spiritual forces of evil, to see Christ’s Kingdom expand through the saving message of His Gospel.
Third, Christians are at times identified as servants or slaves (the same Greek word, δουλος, doulos) of Jesus. In John 15:15, Jesus distinguishes his disciples from mere slaves: a slave obeys his master without knowledge of his master’s purpose; Jesus’s disciples are not servants in this way, they are friends, for Jesus gave to them all that He received from the Father. However, there is a sense in which Christians remain servants of Jesus: they know their master’s plans, yet He is still their master—they are pledged in obedience to their Lord. Elsewhere, Jesus tells a parable of a dishonest manager, concluding that His followers cannot serve both God and money: they must choose whom they will serve, to whom they will be a slave (Luke 16:1-13, cf. Rom. 6:16). When he addresses slaves, Paul identifies them as “bondservants of Christ” along with their fellow believers (1 Cor. 7:22); Paul also calls all Christians, who have been freed from domain of sin, slaves of righteousness, slaves to God (Rom. 6:15-23). They are freed from obedience to sin to be obedient to God, this is in fact their obligation now that they are Christians—how could they continue in sin! Yet, this slavery is true freedom (Rom. 6:22, 2 Cor. 4:17, Gal. 5:1): Peter exhorts his readers to live in their freedom as servants of God (1 Pet. 2:16). Paul also identifies his coworkers as fellow servants of Christ Jesus (Col. 1:7, 4:7). Christ is the Christian’s Lord: He has all rule and authority, we are His people, the citizens of His kingdom, and ought to obey him.
(adapted from the paper, “Appendix 2 – Christ and Culture“)