God rules over all creation (Ps. 103:19; Isa. 66:1; Dan. 5:21). He rules by virtue of such things as His omnipotence, innate authority, and right as Creator. He holds heaven and earth accountable to His law and renders judgment in perfect accord with that law (Ps. 11:4). In a very real sense, all creation is His kingdom, and He is its King.
The Bible commonly speaks of God’s kingship in terms of His relationship with His covenant people. In the Old Testament, He was Israel’s King (1 Sam. 8:7; Isa. 43:15) and they were His holy kingdom (Ex. 19:6; 1 Chron. 17:14). In the New Testament, His kingship over the church (1 Peter 2:9–10; Rev. 1:6; 5:10) is central to the gospel message (Matt. 24:14; Luke 16:16).
Jesus provided a helpful understanding of the nature of God’s universal kingdom and of the role of the church in it when He taught His disciples to pray, “Your kingdom come, your will be done, on earth as it is in heaven” (Matt. 6:10). God’s kingdom is manifested in heaven differently than on earth. In heaven, His will is done perfectly. On earth, sin ensures that His will is done imperfectly at best. The church, though, is to pray for God to expand His heavenly kingdom on earth, so that earth faithfully serves Him as perfectly as heaven does. This is God’s ultimate plan for history.
So the church on earth is called the church militant. God, the great King, has mobilized His people as soldiers in His army (Phil. 2:25; 2 Tim. 2:3; Philem. 2), commanding us to expand the borders of His kingdom by conquering and annexing enemy territory. Primarily, this is a spiritual battle fought on spiritual ground against spiritual enemies (2 Cor. 10:5; Eph. 2:2; 6:12). Nevertheless, because God’s spiritual enemies include unredeemed human beings (Rom. 11:28; Phil. 3:18), the spiritual battle necessarily engages the unbelieving human world.
Correspondingly, one of the main ways that God’s earthly kingdom grows is through the conversion of unbelievers. Before coming to Christ, all people are enemies of God and of His kingdom (Rom. 5:10; Eph. 2:1–3). In saving us, God destroys that enmity and grants us citizenship in His kingdom. The primary visible expression of that kingdom is the covenant community that God rules over—namely, the church. Consequently, the growth of the church, both by expanding into new areas and by increased membership, is the expansion of God’s heavenly kingdom to earth.
growth is victory
The Old Testament promised that God would eventually send His Messiah or Christ to rescue His people from their suffering and exile. The Christ would be a descendant of David who would defeat Israel’s enemies and take His place as Israel’s King. Under His rule, the nation would faithfully return to God and be blessed. Most Jewish theologians in the first century expected this to happen relatively quickly on “the day of the Lord” (Isa. 13:6; Mal. 4:5). When Jesus didn’t do that, they concluded that He wasn’t the Messiah. The New Testament authors recognized the tension that these first-century Jewish expectations created. So they explained that the real failure lay in wrong assumptions about God’s timeline.
Jewish and Christian theologians generally agree that the Old Testament described its own day as “this age” (Matt. 12:32; 1 Cor. 2:6–8; Eph. 1:21). It was characterized by sin, death, suffering, and the subjugation of God’s people. Theologians also agree that the Old Testament looked forward to the future, “the age to come” (Mark 10:30; Luke 18:30; Heb. 6:5), as the messianic age of redemption in which God would destroy all His enemies, would perfect creation, and would pour out blessings on His people. Under the teaching of Jesus and the inspiration of the Holy Spirit, however, the New Testament writers corrected the Jewish error regarding the timing of the two ages. Instead of the age to come replacing this age all at once, the change would happen slowly. The ages would coexist and overlap for a time while God’s kingdom grew. Then, at some unknown time, Jesus would return to complete the transition between the ages.