I am not an adherent to Replacement Theology. Christians do NOT take Israel's place. However, I also do not adhere to theology such as certain books discuss - that of which is purported that Jesus is the Messiah to the Gentiles, but not yet to the Jews. THAT is very easy to disprove in Scripture.
What's my belief? Simply this: Christians join Israel, and become a part of Spiritual Israel. Every Jew is welcome to the Spiritual Israel Tree as well as all Gentiles. To be a member of Spiritual Israel, one must be saved. Jews who have rejected their Messiah - Jesus Christ, have been removed from the Spiritual Israel Tree, but can be grafted back in again, at the moment they become Complete Jews - which is as soon as they have received and accepted the Messiah. This is the mystery of past ages, and it is now solved:
"To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory" -Colossians 1:27
"And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory." -1 Timothy 3:16
Under the Old Covenant/Old Testament, people who were not born Jews could become Jews - spiritually, by proclaiming the God of Israel as their God - the One and only True God. They would then follow the Old Covenant as laid out in the Torah, writings, and prophets. This was recorded in the Old Testament as occurring with many people, and it probably happened a lot more often than was written down.
Under the New Covenant/New Testament - is the Covenant of Grace, Spirit, and Faith. Now the Messiah has come. He came first to the Jews, and then to the Gentiles. Jews and Gentiles are now made one people via the Spiritual Israel Tree.
The prerequisite for joining Spiritual Israel is the same for Gentiles as it is for Jews - believe on Christ, and trust in Him alone for your salvation. Jesus died on the cross to pay the wages of sin - which is death. He did this for us, so that through His shed blood we are washed clean of our sins, and are saved. To receive Christ, one must simply believe. That's it. It's a free gift.
Am I making up this whole thing about the Spiritual Israel Tree? No. I learned it from the Bible, and no other source. I'll show you. Take a look at the below - it's very clear:
Romans 11
1I 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. [In other words, no replacement theology.]
2God hath not cast away his people which he foreknew. Wot ye not what the scripture saith of Elias? how he maketh intercession to God against Israel saying,
3Lord, they have killed thy prophets, and digged down thine altars; and I am left alone, and they seek my life.
4But what saith 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.
5Even so then at this present time also there is a remnant according to the election of grace.
6And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then it is no more grace: otherwise work is no more work.
7What then? Israel hath not obtained that which he seeketh 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.
9And David saith, Let their table be made a snare, and a trap, and a stumblingblock, and a recompence unto them:
10Let their eyes be darkened, that they may not see, and bow down their back alway.
11I say then, Have they stumbled that they should fall? God forbid: but rather through their fall salvation is come unto the Gentiles, for to provoke them to jealousy.
12Now 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 fulness?
13For I speak to you Gentiles, inasmuch as I am the apostle of the Gentiles, I magnify mine office:
14If by any means I may provoke to emulation them which are my flesh, and might save some of them.
15For if the casting away of them be the reconciling of the world, what shall the receiving of them be, but life from the dead?
16For if the firstfruit be holy, the lump is also holy: and if the root be holy, so are the branches.
17And if some of the branches be broken off, and thou, being a wild olive tree Remember, Paul is speaking to the gentiles now. The 'wild olive tree are the gentiles], wert grafted in among them, and with them partakest of the root and fatness of the olive tree;
18Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee.
19Thou wilt say then, The branches were broken off, that I might be grafted in. [This is what the Replacement Theology people basically say, but the Scriptures clearly state here that that is wrong.]
20Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:
21For if God spared not the natural branches, take heed lest he also spare not thee.
22Behold 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 shalt 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 [The unbelieving Jews will be grafted back into the Spiritual Israel Tree if they receive the Messiah - Jesus Christ. They get into the tree the same way Gentiles do - through faith in Christ, and in Christ alone..]
24For if thou gentiles wert cut out of the olive tree which is wild by nature, and wert grafted contrary to nature into a good olive tree Spiritual Israel: how much more shall these, which be the natural branches, be grafted into their own olive tree?
25For 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 fulness of the Gentiles be come in.
26And 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:
27For this is my covenant unto them, when I shall take away their sins.
28As concerning the gospel, they are enemies for your sakes: but as touching the election, they are beloved for the father's sakes.
29For the gifts and calling of God are without repentance.
30For as ye in times past have not believed God, yet have now obtained mercy through their unbelief:
31Even so have these also now not believed, that through your mercy they also may obtain mercy.
32For God hath concluded them all in unbelief, that he might have mercy upon all.
33 O the depth of the riches both of the wisdom and knowledge of God! how unsearchable are his judgments, and his ways past finding out!
34For who hath known the mind of the Lord? or who hath been his counsellor?
35 Or who hath first given to him, and it shall be recompensed unto him again?
36For of him, and through him, and to him, are all things: to whom be glory for ever. Amen.
Gentiles are the "wild olive tree," which are grafted into the "natural olive tree" upon their salvation. Jews are removed from the natural tree because of their rejection of the Messiah, but when they turn to Jesus Christ, they are then grafted back in again. "All Israel shall be saved," because Israel, spiritually are ALL believers. Israelites who have not received Jesus are not counted as Israel anymore, so those Jews who are damned are not counted in the number of "all Israel shall be saved," which are the those who are a part of the Spiritual Israel Tree.
Just as Christians are not under the letter of the Law/Torah, so Christians are also spiritual Israel, regardless of their physical pedigree.
Here are more Scriptures to study about this mystery - The Spiritual Israel Tree:
"For neither they themselves who are circumcised keep the law; but desire to have you circumcised, that they may glory in your flesh. But God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world. For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature born again. And as many as walk according to this rule, peace be on them, and mercy, and upon the Israel of God." -Galatian 6:13-16
"For ye are all the children of God by faith in Christ Jesus. For as many of you as have been baptized into Christ have put on Christ. 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. And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise." -Galatians 3:26-29
"He therefore that ministereth to you the Spirit, and worketh miracles among you, doeth he it by the works of the law, or by the hearing of faith? Even as Abraham believed God, and it was accounted to him for righteousness. Know ye therefore that they which are of faith, the same are the children of Abraham. 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. So then they which be of faith are blessed with faithful Abraham. 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. But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith. And the law is not of faith: but, The man that doeth them shall live in them. 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: That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith." -Galatians 3:5-14
Next in this series - "The Christian's relationship to the Hebrew form of Yah"