What do you say when someone tells you that Israel is no longer the Jewish people, but the Church?
Theologically speaking, when Christians identify the promises, the covenants and the warnings to Israel with the Church, it is not an improper application—but it might well be a bad interpretation.
When you answer a person, it is good to explain the important difference between application and interpretation of Scripture. Many things given to Israel, be they blessings, promises or warnings, also apply to the Church as the people of God. But to interpret Israel as the Church is different. Those who say to read the Church” everywhere the Bible mentions Israel are basically saying that the Church has replaced Israel. That is not an application; it is an interpretation that I believe is inaccurate.
I would tell that person that it is true that Israel is a metaphor for all believers, but the fact that it is used as a metaphor does not mean that Israel does not have a literal dimension. You might point out that when Paul identified himself as an Israelite in Romans 11:1, he made a point of explaining which tribe he was from (Benjamin). Paul was obviously talking about being an Israelite not only in a spiritual, but in a literal, physical sense as well. The people of Israel are not synonymous with the people of the Church. If we know anything at all about the Church, we know that it consists of saved people who are a part of the New Covenant according to Jeremiah 31:31. If the Church is Israel, then why does Paul in Romans 10:1 say, “Brethren, my heart’s desire and prayer to God for Israel is that they may be saved”?
The language would seem to indicate that the brethren to whom he is speaking are the Church, and the Israel of whom he is speaking is the Jewish people. There are many other passages in the New Testament that show how the literal people of Israel continue in a covenant relationship with God. That covenant does not bring salvation, but it includes many promises that I believe God will keep.