I've often heard it said, as a primary reason for holding Israel and the Church apart as two completely separate theological entities, that the Church is never called "Israel" in the NT. I'm sure it won't surprise anyone who has frequented this blog to know that I disagree both with this premise and with its conclusion.
According to Scripture, “Israel” didn’t merely refer to an ethnic people group or a nation abstractly, but referred also to the elect, the chosen family of the God of Abraham, Isaac and Jacob. So if anyone was engaged in redefining who the covenant people of God really were—like John the Baptist, Jesus and Paul all did—then that person was essentially redefining who “Israel” was. “Not all are Israel who are of Israel”, Paul says, acknowledging the ethnic sense in which someone can be “of Israel” and yet claiming polemically that they do not thereby stand in the covenantal “Israel”, i.e. the children of promise who are counted as the “seed”.
Now, as many have noted, standing alone it’s true that this phrase in Romans 9 doesn’t necessarily imply that Gentiles are included in the true “Israel”; in and of itself it only insists negatively that not all Jews are included in that company. However, Paul doesn’t mean for that to be a stand-alone statement. He goes on to state positively: “But the children of the promise are counted as the seed”. The question is, Who are the ones that are counted as Abraham’s descendants? Considering the foundation he has laid already in chap. 4 and following the logic of the present passage to his own conclusion in vv. 23-33, it seems hard to deny that Paul includes Gentiles in the “children of promise”, the “seed”, and thus in the true eschatological “Israel” of v. 6.
But aside from this or any other passage in the NT where the church is identified as Israel, I think there is a bigger problem with the premise mentioned above, and that is the assumption that if a word is not present then the idea is not present either. If the NT writers don't use the word "Israel" in reference to the Church, so this line of thought goes, then they must not have believed that the Church carried the calling and promises of Israel. But besides the now singularly controversial title of “Israel”, Paul and the other NT writers used many titles for the Church that in the first century carried the equivalent covenantal meaning, one that's not commonly recognized actually being the term “church” itself, the Septuagint term for the “assembly” of Israel—or as Steven says it in Acts 7 when referring to the children of Israel at Mt. Sinai, the “congregation in the wilderness”.
The term “saints” is another one that we don't commonly think of as a synonym for Israel, but a quick brush through its occurrences in the OT should give us a clue. After Paul says that the Gentile Christians in Ephesus were “once aliens of the commonwealth of Israel”, he then goes on to say that they “are no longer strangers and foreigners, but fellow citizens with the saints”. Notice that he doesn't call the Ephesian Christians themselves “saints” here, but instead says that they've become “fellow citizens with the saints”. Of course, that's not because he doesn't think they are saints; in fact his point is exactly the opposite. But this does show how the designation “saints” was used in Paul's day—as a synonym for the nation of Israel, Jews, the historic people of God, over and against the pagan Gentiles.
This is why it was such a dramatic shift in thinking—a complete change of worldview—when the Lord commanded Peter to share the gospel with the household of the God-fearing centurion Cornelius, and when upon doing so that whole family was saved and filled with the Spirit. Luke notes that all the Christian Jews who saw this were astonished, because the Lord showed no partiality, made no distinction, and poured out the gift of the Holy Spirit upon the Gentiles also.
But there are many other even more overt titles that deserve recognition: “Sons of God”, for one, or “kingdom of priests”, or “special people”, or “seed of Abraham”—or even “the Circumcision”. These were all synonyms for “Israel” in the first century, and they are all used by the NT writers to refer to the renewed Jew-plus-Gentile family of God in the Messiah. Using any one of those terms to refer to an uncircumcised Gentile would be absolutely offensive to the sensibilities of a Second-Temple Jew, and that's precisely the point. So I don't see how referring to that renewed family as “Israel” would be any more of a radical leap, either theologically, culturally or socially, than any other of the Jewish designations that were broadened by the early Church to include Gentiles.
Why should that one term be the odd man out when the NT writers were so liberal with all of its synonyms? Why should it be so offensive, for instance, to call the multi-ethnic family of God “Israel” and yet not be offensive to call them “Abraham’s seed” or the “children of promise”? I submit that this is not because those terms were any less offensive in the world of first century Judaism, but that we in the twenty-first century West have lost touch with their essential Israel-meaning. This is thus a perfect example of a place where the Church needs (ironically in the words of David Pawson) to “deGreece” its thinking and reading of Scripture.