A verse that has been used more than once by those trying to convince me that the church replaces Israel in God’s eternal plan is Romans 9:6:
For not all who are descended from Israel are Israel.
What I am supposed to understand is that it is not physical Israel that receives God’s blessing but spiritual Israel (the church).
They then go to Romans 2:29:
A man is a Jew if he is one inwardly; and circumcision is circumcision of the heart, by the Spirit, not by the written code.
Physical circumcision is irrelevant and the only Jews who are saved are those who are in the church. We can thank Paul for clearing this up for us, lest the Old Testament lead us astray.
The reality here, however, as in so many other places, is that Paul is entirely consistent with the OT. When Paul wrote the words quoted above, he was merely explaining what prophets like Jeremiah had already said (9:25-26).
“The days are coming,” declares the Lord, “when I will punish all who are circumcised only in the flesh— Egypt, Judah, Edom, Ammon, Moab and all who live in the desert in distant places. For all these nations are really uncircumcised, and even the whole house of Israel is uncircumcised in heart.”
The prophets knew that not all Israel was Israel, that not all who were physically circumcised were spiritually circumcised. Yet they could still say, as Jeremiah did:
This is what the Lord says, he who appoints the sun to shine by day, who decrees the moon and stars to shine by night, who stirs up the sea so that its waves roar— the Lord Almighty is his name: “Only if these decrees vanish from my sight,” declares the Lord, “will the descendants of Israel ever cease to be a nation before me (Jer 31:35–36).
How can this be? How can the whole house of Israel be uncircumcised and yet be promised that they would never cease to be a nation before God?
The answer is not that Israel would be swallowed up in the church and forever cease to exist. The answer is that:
On that day a fountain will be opened to the house of David and the inhabitants of Jerusalem, to cleanse them from sin and impurity (Zech 13:1).
The answer is that in the future God will grant spiritual circumcision to those who are physically circumcised.
The LORD your God will circumcise your hearts and the hearts of your descendants, so that you may love him with all your heart and with all your soul, and live (Deut 30:6).
In this way God will receive great glory. This may not be how we would do it, but it is how God designed it. As Paul concluded his own study of this very topic, he wrote:
Oh, the depth of the riches of the wisdom and knowledge of God! How unsearchable his judgments, and his paths beyond tracing out!…To him be the glory forever! Amen (Rom 11:33-36).