My Reformation Study Bible, ed. by R.C. Sproul, Sr., (Nashville, TN: Thomas Nelson, 1995) offers an exposition upon “Christians in the World” (p. 1889). Therein it notes:
The word ‘world’ in the New Testament is sometimes used as in the Old Testament to mean this earth, the good natural order that God created. Usually, however, it designates humanity as a whole, now fallen into sin and moral disorder, radically opposed to God. People in the world incur guilt and shame by their misuse of created things. Paul can even speak of creation itself yearning for deliverance from the evil occasioned by the fall of Adam and Eve (Rom. 8:20-23).
Christians are sent into the world of fallen humanity by their Lord (John 17:18) to witness to it about God’s Christ and His Kingdom (Matt. 24:14; c.f. Rom. 10:18; Col. 1:6, 23) and to serve its needs. But they are to do so without falling victim to its materialism (Matt. 6:19-24, 32), its lack of concern about God and eternity (Luke 12:13-21) and its pursuit of pleasure and status above all else (1 John 2:15-17). The outlook and mindset of human societies reflect more of the pride seen in Satan, who for now continues to influence them (John 14:30; 2 Cor. 4:4; 1 John 5:19; c.f. Luke 4:5-7), than the humility seen in Christ. Christians, like Christ Himself, are to empathize with people’s anxieties and needs in order to serve them and communicate God’s love for them effectively.
Christians are to consider themselves pilgrims in this fallen world, through which they momentarily pass as they travel home to God (1 Peter 2:11). The Bible sanctions neither monastic withdrawal from this world (John 17:15) nor worldliness (Titus 2:15). Jesus encourages His disciples to match the ingenuity of the unredeemed who use their resources to further their goals, but specifies that the disciples’ proper goals have to do, not with earthly security, but with heavenly glory (Luke 16:9). Christians are to be different from those around them, observing God’s moral absolutes, practicing love, and not losing their dignity as bearers of God’s image (Rom. 12:2; Eph. 4:17-24; Col. 3:5-11). Separation from fallen humanity’s values and lifestyles is a prerequisite for practicing Christian likeness in positive terms (Eph. 4:25-5:17).
The Christian’s appointed task, therefore, is threefold. The church’s main mandate is evangelism (Matt 28:19, 20; Luke 24:46-48), and every Christian must seek to further the conversion of unbelievers, not least by the example of one’s changed life (1 Pet. 2:12). Also, love of neighbor should constantly lead the Christian into deeds of mercy for all people, believers and unbelievers alike. Finally, Christians are caleld to fulfill the ‘cultural mandate’ that God gave to mankind at creation (Gen. 1:28-30; Ps. 8:6-8). Humanity was created to mange God’s world, and this stewardship is part of the human vocation in Christ, with God’s honor and the good of others as its goal. The Protestant ‘work ethic’ is essentially a religious discipline, the fulfillment of a divine ‘calling’ to be stewards of God’s creation.
Knowing that God in providential kindness and forbearance continues, in the face of human sin, to preserve and enrich His erring world (Acts 14:16, 17). Christians are to involve themselves in all forms of lawful human activity. By acting in accord with Christian values, they will become salt (a preservative agent) and light (an illumination that shows the way) in the human community (Matt. 5:13-16). As Christians thus fulfill their vocation, they will transform the cultures around them.