Eerdman's New Bible Dictionary, in discussing the Kingdom of God, traces views and interpretations of the concept of the Kingdom through history. The early Roman Catholic Church developed the belief that the Kingdom had already come in the form of the church. Its leaders were seen as leaders of the Kingdom; where the church spread its power and authority was viewed as synonymous with the boundaries of the Kingdom (Eerdmans, Grand Rapids, 1962, p. 696).
"In their resistance to the Roman Catholic hierarchy, the Reformers laid chief emphasis on the spiritual and invisible significance of the kingdom and readily (and wrongly) invoked Luke xvii. 20f. in support of this." Protestant churches continued this drift in a reaction to abuses of power and developed an emphasis upon social and community programs. "The coming of the kingdom consists in the forward march of social righteousness and communal development" (ibid.).
The article concludes with the summation that returns to the duality of salvation and a kingdom. "In contrast to these spiritualizing, moralistic, and evolutionary interpretations of the kingdom, New Testament scholarship is rightly laying stress again on the original significance of the kingdom in Jesus' preaching-a significance bound up in the history of salvation and eschatology [study of events surrounding Christ's return]" (ibid.).
Zondervan's Pictorial Bible Encyclopedia concludes that neither the idea of a Kingdom of God without a Savior nor the idea of a Savior without a Kingdom of God "can stand on its own" and "each can be defended only at the cost of explaining away, often by dubious methods, the evidence for the other" (Vol. III, p. 804)
There is a kingdom yet to come from God. When Jesus instructed believers to pray for the Kingdom to come (Matthew 6:10), "the verb ...preclud[es] the notion of gradual progress and development, and impl[ies] a sudden catastrophe ..." (Vine's Expository Dictionary of Old and New Testament Words, Thomas Nelson Publishers, Nashville, 1985, p. 345).
Zondervan's Bible Encyclopedia concludes its article on the Kingdom: "Although the Kingdom was truly present in the ministry of Jesus, He also spoke of it as a future entity and told His disciples to pray for its coming (Matthew 6:10; cf. Luke 11:12) ... By this manner of speaking, Jesus was referring to the age to come (Mark 10:30; cf. Luke 18:30) which was associated with the coming of the Son of man, the resurrection of the dead and the setting up of the eternal realm of bliss ..." (Vol. III, p. 806, emphasis added). GN