Paul warns us Gentiles, "not to be ignorant of this mystery (Israel), lest we become wise in our own conceit", because Israel's blindness to the gospel will only continue "until the fullness of the Gentiles come in". (Romans 11: 25)
Isaiah foretold that in the last days, "the Lord shall set his hand again the second time. . . . . and shall assemble the outcasts of Israel. . . . . from the four corners of the earth. . . . . . and the adversaries of Judah shall be cut off. " (Isaiah 11: 11-13)
Amos adds significantly, "and they shall no more be pulled up out of their land which I have given them, says the Lord your God". (Amos 9: 15)
The Gentile age, revealed to Daniel, is ending; and with it the Church age at the "catching away" of Christ's bride; then the Kingdom shall come to earth. (Daniel 2: 34, 35) ·
Sometime during this transition physical Israel, regathered in the land, will be brought to life spiritually: "And I will make them one nation in the land of Israel. . . . and they all shall have one shepherd. . . . . I will be their God and they shall be my people. . . and the heathen shall know that I the Lord do sanctify. Israel"(Ezekiel 37: 22)
James addresses his epistle to "the twelve tribes in the Diaspora. Clearly, he saw the Jewish Christians, to whom he was writing, as still Israelites. He describes their meeting as a "synagogue," (2.2). Peter was given as "apostleship to the circumcision (i.e., to the Jews)" (Gal. 2:8). This is why Peter's first epistle is written from Babylonia, where the largest First Century Jewish community resided (1 Peter 5:13), and was addressed to "chosen exiles of the Diaspora." (1 Peter 1:1)
Paul himself was a Jew, and also the chosen apostle to the Gentiles. (There is not one even one non-Jewish apostle in the New Testament). Paul's epistle to the Romans is the theological heart of the New Covenant. Chapters 9-11 contain his mature teaching about Israel.
Romans 9-11 - The Olive Tree - The Church DOES NOT Replace Israel!
The following is a summary list of the points Paul makes in Romans 9-11 in his great teaching on the nation of Israel and how she relates to God's prophetic time clock and future:
The Jews, even in their rejection of Jesus are STILL Israelites: - Romans 9:4 - ...Who are Israelites; to whom pertain the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises;
To Israel still belong the ADOPTION, the GLORY, the COVENANTS (including the New COVENANT), the GIVING OF THE LAW, the SERVICE OF GOD, and THE PROMISES (9:4c)
The main body of Israel has forfeited salvation through rejecting the Messiah - Romans 9:30-33; 10:21 - What shall we say then? That the Gentiles, which followed not after righteousness, have attained to righteousness, even the righteousness which is of faith. [31] But Israel, which followed after the law of righteousness, hath not attained to the law of righteousness. [32] Wherefore? Because they sought it not by faith, but as it were by the works of the law. For they stumbled at that stumblingstone; [33] As it is written, Behold, I lay in Sion a stumblingstone and rock of offence: and whosoever believeth on him shall not be ashamed; Romans 10:21 - But to Israel he saith, All day long I have stretched forth my hands unto a disobedient and gainsaying people.
Paul desires and PRAYS for their salvation - there is NOT anti-Jewishness in Paul's heart - quite the opposite - Romans 9:1-3 - I say the truth in Christ, I lie not, my conscience also bearing me witness in the Holy Ghost, [2] That I have great heaviness and continual sorrow in my heart. [3] For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh:
Israel is NOT finally rejected (Romans 11:1-2). Even in OT times, there was only a remnant of true believers among a nation largely composed of unbelievers. In Paul's day, nothing had changed (Romans 11:2-6 - I say then, Hath God cast away his people? God forbid. For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin. [2] God hath not cast away his people which he foreknew. Do you not know what the scripture said of Elias? how he makes intercession to God against Israel, saying, [3] Lord, they have killed thy prophets, and digged down thine altars; and I am left alone, and they seek my life. [4] But what said the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal. [5] Even so then at this present time also there is a remnant according to the election of grace. [6] And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then is it no more grace: otherwise work is no more work.
God has judicially blinded the unbelieving majority to the truth - Romans 11:7-10 - What then? Israel hath not obtained that which he seeks for; but the election hath obtained it, and the rest were blinded [8] (According as it is written, God hath given them the spirit of slumber, eyes that they should not see, and ears that they should not hear

unto this day. [9] And David said, Let their table be made a snare, and a trap, and a stumbling block, and a recompense unto them: [10] Let their eyes be darkened, that they may not see, and bow down their back always.
Israel has paid the price of rejection to give the Gentiles a chance. However, their restoration is assure and will be "life from the dead." - Romans 11:12-16 Now if the fall of them be the riches of the world, and the diminishing of them the riches of the Gentiles; how much more their fullness? [13] For I speak to you Gentiles, inasmuch as I am the apostle of the Gentiles, I magnify mine office: [14] If by any means I may provoke to emulation them which are my flesh, and might save some of them. [15] For if the casting away of them be the reconciling of the world, what shall the receiving of them be, but life from the dead? [16] For if the first fruit be holy, the lump is also holy: and if the root be holy, so are the branches.
Unbelieving Jews are like olive branches cut off from their own tree. Believingg Gentiles are wild live branches grafted in. But Gentiles are not to BOAST AGAINST THE JEWS, because God is able to graft them in again. The Olive Root speaks of the spiritual riches, which flow from God via the Patriarchs, which the Church (comprised of Jews and Gentiles) now enjoys, and which unbelieving Israel has temporarily lost - Romans 11:17-24 -And if some of the branches be broken off, and thou, being a wild olive tree, were grafted in among them, and with them partakes of the root and fatness of the olive tree; [18] Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee. [19] Thou wilt say then, The branches were broken off, that I might be grafted in. [20] Well; because of unbelief they were broken off, and you stand by faith. Be not high minded, but fear: [21] For if God spared not the natural branches, take heed lest he also spare not thee. [22] Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shall be cut off. [23] And they also, if they abide not still in unbelief, shall be grafted in: for God is able to graft them in again. [24] For if thou were cut out of the olive tree which is wild by nature, and were grafted contrary to nature into a good olive tree: how much more shall these, which be the natural branches, be grafted into their own olive tree?
A Future national repentance is expected for Israel. This is laid before us as a mystery (a secret which can now be revealed - Romans 11:25-27). Compare Zechariah 12:10, where the prophet also speaks of a national repentance towards a Messiah, who is also God. Romans 11:25-27 - For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fullness of the Gentiles be come in. [26] And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: [27] For this is my covenant unto them, when I shall take away their sins.
Israel, even in its unbelief, is chosen and loved by God - Romans 11:28 - As concerning the gospel, they are enemies for your sakes: but as touching the election, they are beloved for the fathers' sakes.
"As concerning the gospel they are enemies for "your sakes" (i.e. YOU GENTILES). This alone should bring about great thankfulness and love towards the Jews from Gentile Christians.
"The gifts and calling of God are irrevocable." Romans 11:29 - This is firm ground on which to believe that God has not rejected Israel.
Paul still identifies himself as a Jew, after coming a Christian (Acts 21:39)Acts 21:39 - But Paul said, I am a man which am a Jew of Tarsus, a city in Cilicia, a citizen of no mean city: and, I beseech thee, suffer me to speak unto the people.
The NT epistle addressed to the Hebrews is a warning to Jewish believers not to return to Judaism as a religious hope, but it clearly still sees these believers as Jewish. It's not a militant call against the Jewish race as some church fathers have taught.