Postmillennialism
A distinguishing characteristic of many advocates of covenant theology is their optimistic view of the future. They believe the Kingdom of God will expand throughout the world in agreement with the Great Commission which Jesus gave the Apostles prior to taking his throne in heaven next to the Father. Postmillennials believe the mission for the corporate church is to actually extend the Kingdom of God, both personally and culturally, into all the world in fulfillment of the Great Commission given to Christians by Christ.
The Great Commission
16 Then the eleven disciples went to Galilee, to the mountain where Jesus had told them to go. 17 When they saw him, they worshiped him; but some doubted. 18 Then Jesus came to them and said, “All authority in heaven and on earth has been given to me. 19 Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.” (Mathew 28: 16 - 20, NIV)
Postmils believe this is the last command given to all Christians by the risen King Jesus. They believe all Christians are to be faithful to this last commission given by Jesus until he returns - no matter what the apparent historical or eschatological perspective looks like. Postmils believe that even if it is apparent that the end of the world is surely going to occur next week, we are still called to be faithful to this last command and continue to spread the Kingdom of God by first evangelizing, and then discipling entire nations and people groups for Jesus.
This biblical paradigm has had a powerful influence in church history. These Christian continued their work even when it was apparent there was not much hope the Great Commission would ever succeed in history. Postmils believe that even though they may not see the immediate fruit from their labors, they were paving the way for future generations of Christians to follow by bringing the Gospel to places where it had not previously gone. They were not thwarted from their mission by pessimistic views of the future.
Once these missionaries penetrated areas where the Gospel had never been before, this only represented the beginning of the work to the people in those areas. Postmils have a long-term view of the future and work to disciple the people groups and nations so effectively that a Christian culture develops as a result of their efforts. In this way, the Kingdom of God is expanded as the people are not only exposed to the saving message of the Gospel, but such effective discipleship follows that the converted people learn to live according to the principles found in the bible - both personally and culturally. Postmils believe biblical truth should eventually lead to a national cultural transformation as the converted people come under the lordship of Jesus and live by biblical principles.
The following video clip gives a historical overview of this perspective and its impact in world missions.