Paul told the Corinthians that Christ died for the Jews, and for all men:

(2 Cor 5:14-15 KJV) For the love of Christ constraineth us; because we thus judge, that if one died for all, then were all dead: {15} And that he died for all, that they which live should not henceforth live unto themselves, but unto him which died for them, and rose again.

Jesus came to the Jews first. The Gentiles being added to Israel fulfills several Old Testament prophecies: Psalm 18:49, Deut. 32:43, Psalm 117:1, Isa. 11:1,10:

(Psa 18:49 KJV) Therefore will I give thanks unto thee, O LORD, among the heathen, and sing praises unto thy name.

(Deu 32:43 KJV) Rejoice, O ye nations, with his people: for he will avenge the blood of his servants, and will render vengeance to his adversaries, and will be merciful unto his land, and to his people.

(Psa 117:1 KJV) O Praise the LORD, all ye nations: praise him, all ye people.

(Isa 11:1 KJV) And there shall come forth a rod out of the stem of Jesse, and a Branch shall grow out of his roots: . . . . {10} And in that day there shall be a root of Jesse, which shall stand for an ensign of the people; to it shall the Gentiles seek: and his rest shall be glorious.

The Gentiles are partakers of the blessing of Romans 15:26-27. The Gospel records clearly demonstrate that the New Covenant was offered to the Jews first. In Matthew 10, Jesus sent the disciples to preach the Gospel only to the nation of Israel. Only after the Jewish leadership rejected Christ was the Great Commission expanded to include all nations [Matt:28:18-20].

(Mat 28:18-20 KJV) And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. {19} Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: {20} Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.

(Rom 1:16 KJV) For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.

(Rom 15:8-12 KJV) Now I say that Jesus Christ was a minister of the circumcision for the truth of God, to confirm the promises made unto the fathers: {9} And that the Gentiles might glorify God for his mercy; as it is written, For this cause I will confess to thee among the Gentiles, and sing unto thy name. {10} And again he saith, Rejoice, ye Gentiles, with his people. {11} And again, Praise the Lord, all ye Gentiles; and laud him, all ye people. {12} And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust.

(Rom 15:26-27 KJV) For it hath pleased them of Macedonia and Achaia to make a certain contribution for the poor saints which are at Jerusalem. {27} It hath pleased them verily; and their debtors they are. For if the Gentiles have been made partakers of their spiritual things, their duty is also to minister unto them in carnal things.

GENTILE CHRISTIANS ARE "COUNTED FOR THE SEED" AND CHILDREN OF GOD

(Rom 9:6-8 KJV) Not as though the word of God hath taken none effect. For they are not all Israel, which are of Israel: {7} Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called. {8} That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.

(Rom 9:30-33 KJV) 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.

THE BELIEVING JEWS AND GENTILES WOULD BE MADE TO BE ONE FLOCK

Jesus taught that the Gentiles who believed would be united with the believing remnant of Israel in one "fold" with one "Shepherd":

(John 10:16 KJV) And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd.

THE SEED OF ABRAHAM AS GOD'S ADOPTED SONS WOULD INHERIT THE EARTH

As adopted sons of God, we also will receive the promise to Israel to inherit the earth.

(Rom 4:13-16 KJV) For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith. {14} For if they which are of the law be heirs, faith is made void, and the promise made of none effect: {15} Because the law worketh wrath: for where no law is, there is no transgression. {16} Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,

We are the adopted children of God under the New Covenant. Because Christ is the heir, and we are in Christ, we are heirs of the Old Testament promises of the Millennial Kingdom of God.

(Gal 3:6-29 KJV) Even as Abraham believed God, and it was accounted to him for righteousness. {7} Know ye therefore that they which are of faith, the same are the children of Abraham. {8} And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed. {9} So then they which be of faith are blessed with faithful Abraham. {10} For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them. {11} But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith. {12} And the law is not of faith: but, The man that doeth them shall live in them. {13} Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree: {14} That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith. {15} Brethren, I speak after the manner of men; Though it be but a man's covenant, yet if it be confirmed, no man disannulleth, or addeth thereto. {16} Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ. {17} And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect. {18} For if the inheritance be of the law, it is no more of promise: but God gave it to Abraham by promise. {19} Wherefore then serveth the law? It was added because of transgressions, till the seed should come to whom the promise was made; and it was ordained by angels in the hand of a mediator. {20} Now a mediator is not a mediator of one, but God is one. {21} Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law. {22} But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe. {23} But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed. {24} Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith. {25} But after that faith is come, we are no longer under a schoolmaster. {26} For ye are all the children of God by faith in Christ Jesus. {27} For as many of you as have been baptized into Christ have put on Christ. {28} There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. {29} And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise.

(Mat 5:5 KJV) Blessed are the meek: for they shall inherit the earth.