I recently picked up an older book that gives a detailed summary of the different New Testament images for the church. It’s by Paul Minear and is called Images of the Church in the New Testament (1960). I’m not finished with it, but so far it has been pretty interesting and helpful. Below is a helpful excerpt of a section where Minear summarizes the political and national analogies of the church found in the NT. One is “Israel”:
This designation [Israel] was given most directly in a letter of Paul to the churches of Galatia. These churches were composed largely of Gentiles who had been suffering from the inroads of the Judaizers. Yet Paul closed his sharpest polemic against the Judaizers by the surprising benediction: ‘Peace and mercy be upon…the Israel of God.’ Those waging bitter battles against the Jews were thus reminded that they themselves were God’s Israel. This Israel included all who walked according to the rule that circumcision ‘counts for nothing’ (Gal. 6:15-16). Even though two groups were thus contesting the name, Paul did not fall back upon a concept of two Israels, the old and the new, or the false and the true. He defined God’s Israel as one people, as measured qualitatively by God’s mercy in the cross of Christ
This same qualification appears in other writings that speak variously of the church as the commonwealth of Israel (Eph. 2:12), as the house of Israel (Heb. 8:8-10); 11:25), as the sons of Israel (Rev. 2:14), or simply as my people Israel. It is in relation to this people that the mission of the Messiah is understood. He is sent to Israel (Matt. 15:24), as its shepherd, ruler, and judge, to bring repentance and forgiveness (Acts 5:31). His advent is designed for Israel’s glory (Luke 2:32), and for the rising and falling of many in Israel (v. 34). Though many in Israel do fall, nowhere in the New Testament is it conceded that God had rejected or could reject ‘his people whom he foreknew’ (Rom. 11:2).
In its liturgy and life the church knows itself to be addressed by the familiar words: ‘Hear O Israel’ (Mk 12:29). Its God is none other than the God of Israel, and the fulfillment of all his purposes is shaped by the terms of his steadfast love for Israel. To be sure, some Christian writers appealed to the fact that a new covenant had been promised by the old, but they continued to insist that this new covenant was one that God established with the house of Israel (Heb. 8:8-13).
So strong is this sense of solidarity that one must conclude that the continuity between the two Testaments is grounded in the fact that both tell the story of how the same God fulfills his covenant promises to the same people. It is significant that no change of name was considered necessary to make room for the new community. The Israel to whom the gospel comes and through whom the mission to the world is accomplished is the same Israel to whom the promise had been given.