A straightforward reading of Romans 11 indicates that Israel and the Church in some sense “should be” one people — Jew and Gentile united in Messiah, and indeed ultimately will be one. But due to various forms of disobedience there is lopping and pruning and grafting which occur in the meantime, such that the unified olive tree is not presently seen in this world for what it should be.

There is a great deal I wish to say on this topic, both further establishing the case from various angles and also answering and clarifying many questions which arise. But first, many people will want to know: why should I care? Is this merely abstract theology combined with speculative prophecy, or does it have any impact on my day-to-day life?

Answer: one reason it matters immensely is because with privilege comes responsibility. If the Church is, at least in some sense, a continuation of Israel then she inherits not only the precious promises and blessings of the Old Testament but also the duties of God’s “firstborn son” and beloved bride as described therein! Let three examples suffice for now:

1. Abraham was blessed in order to be a blessing to all the families of the earth (Gen 12:2). If God rebuked the “cows of Bashan” (Amos 4:1) whenever “Jeshurun grew fat” (Deut 32:15), then how much worse is it allow the blessings of the New Covenant to terminate in self-indulgence!
2. After repeated chastenings and escalated warnings, God finally sent Israel and Judah into exile because of their adulterous idolatries. Insofar as the Church of Christ is “the Israel of God” (Gal 6:16), she should expect to experience her own Babylonian exile to the extent that she prostitutes herself after other lovers.
3. Since the days of Egypt, the Hebrew descendants of Jacob have always been set apart as a distinct people in the world. Through four millennia they have been attacked by a multitude of different enemies on every side, but have continued to maintain an open, public identity in the world. In other words, generally speaking, Judaism doesn’t go underground. Jews might physically hide themselves from their persecutors (like in Nazi Germany), but they don’t hide their connection to Judaism. This is related to point #1 above because God’s people are always meant to be a LIGHT to the world (Isa 42:6, 49:6, cmp. Mt 5:14-16). If our form of “Christianity” lacks the fortitude to bear OPEN, PUBLIC witness to Christ in ALL the nations of the earth, including the “closed” and “hostile” ones, then in that regard we are less faithful witnesses than countless Jews who — despite not believing in Messiah — have maintained their identity as Israelites through centuries of fiery opposition.

Moreover, these are not merely examples that I have personally thought up. The Book of Revelation addresses all three of these issues, sternly warning the followers of Jesus that they are in danger of repeating all the major mistakes that the People of God made in ages past.