Note: All Scripture quotations found in this article are from the text of the Authorized King James Version of the Bible.
Replacement theology, also called Supersessionism, is the false teaching that the Body of Christ/Church has replaced the nation of Israel regarding the plan, purpose and promises of God. These heretics teach that Israel is no longer God's chosen people, instead the Church has replaced them. This view is far from Biblical. Those that believe this false doctrine will often go to Romans 11 to prove their heresy.
Romans 11:1 "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."
In the above verse, the phrase "his people" is a reference to Israel, not the Church or "spiritual Jews". We know this because Paul gives his genealogical credentials. This verse is talking about the physical Israel and the physical tribes of Israel. Paul labels himself an Israelite and also calls himself a Jew by nature in Galatians.
Galatians 2:15 "We who are Jews by nature, and not sinners of the Gentiles,"
Every time the phrase "his people" shows up it will be a reference to the nation of Israel more than 90 percent of the time.
Deuteronomy 7:6 "For thou art an holy people unto the LORD thy God: the LORD thy God hath chosen thee to be a special people unto himself, above all people that are upon the face of the earth."
Exodus 3:7 "And the LORD said, I have surely seen the affliction of my people which are in Egypt, and have heard their cry by reason of their taskmasters; for I know their sorrows;"
Exodus 3:10 "Come now therefore, and I will send thee unto Pharaoh, that thou mayest bring forth my people the children of Israel out of Egypt."
Exodus 8:1 "And the LORD spake unto Moses, Go unto Pharaoh, and say unto him, Thus saith the LORD, Let my people go, that they may serve me."
Exodus 19:5 "Now therefore, if ye will obey my voice indeed, and keep my covenant, then ye shall be a peculiar treasure unto me above all people: for all the earth is mine:"
Ignore the phony British "Israelites". An Israelite and a Jew are the same thing in the Bible. Do not worry about figuring out where the real tribes are today. In the Tribulation, God will choose 12,000 Jews from each tribe to be witnesses during the that time of Jacob's Trouble.
Note: As Christians, we are to bless Israel. It would be wise not to bash Jews. Many physical Jews are located in Israel today. The government in Israel is not perfect (no government is), but it is not our job to put them down because America along with every other nation, besides Israel, is "as a drop of a bucket" (Isa. 40:15). Let us leave the judgment to God because God is very consistent with judging those that curse Israel. Any serious Bible Believer should be Pro-Israel.
The below verse describes one of the mysteries in the New Testament. This passage proves that God is not done with the nation of Israel. Right now, Israel as a nation is spiritually blind, but only partly because there are still some Jews that are receiving Jesus Christ as their Saviour in the Church Age today.
Romans 11:25 "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 fulness 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."
When the fulness of the Gentiles comes to an end, the Rapture will take place, which is where the Body of Christ is taken up to meet Jesus in the clouds. When Jesus returns at the end of the Tribulation, Israel will be restored and the Jews remaining will accept Christ as Saviour according to verse 26 (Zech. 12:10-14). This is when God establishes a new covenant with Israel (Heb. 8:8-12).
Although, the below verse is speaking of a spiritual Jew, God has never once said in His word that He is through with the physical Jew. We know this because in the very next chapter, the physical Jew is mentioned as the author of scripture (Rom. 3:1-2). It is true that there is neither Jew, nor Gentile in Christ (Gal. 3:28), but outside of Christ there is both.
Romans 2:28 "For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: 29 But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God."
The below passage is another passage that the Replacement crowd uses to "prove" their error. In reality, this passage is saying that although most of the Jews rejected the truth, there were still some that accepted Christ.
Romans 9:6 "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."
There are two Israels talked about in the passage. One is just the physical Jew and the other is the physical Jew, who is also a spiritual Jew. The Israel of God in Galatians 6:16 are saved Israelites who constitute the true nation of Israel, spiritually. This passage in no way teaches that Israel has been replaced with the Church. Replacement theologians simply privately interpret scripture to fit their theology.
The Church and Israel are not the same thing. The Church does not get the promises that God gave Israel. The promises that God gave Israel were unconditional and not based on whether Israel stayed faithful or not. The promises were based on the faithfulness of God alone. Read Romans 11:11-29 and notice that the context is the unconditional promises of Israel.
Romans 11:29 "For the gifts and calling of God are without repentance."
If God lied to Israel about their promises then maybe we as believers should be worried about our promise of eternal security. As for me, I believe what God said, exactly how He said it in His word. Israel has not been replaced by the Church or any other group. God is not done with Israel because He will restore His people at the Second Coming as the scriptures teach in Revelation and all throughout the Old and New Testament.