In order to argue that there’s only one Gospel in Scripture (and that the result of salvation is the same for everyone), it helps to first believe that the Israel of God and the church known as the body of Christ are actually one and the same entity, and that references to Israel in Scripture are actually references to said church. Of course, when you study Scripture carefully, it quickly becomes apparent that the body of Christ is not the same group of people as those known as the Israel of God. In fact, this is made quite obvious by reading the very passage in which the Israel of God is named (Galatians 6:16), where peace is wished upon “as many as walk according to this rule” — referring to those in the body of Christ who follow the teaching Paul had just given — and upon the Israel of God as well. That these can’t be the same people is made obvious by the words “and upon” (καὶ ἐπὶ in the original Greek), since “and upon” tells us there are two separate groups of people being wished peace by Paul there.
Likewise, we can also see that Israel is a distinct group from the Gentiles in the body of Christ when Paul refers to Israel as the cultivated, natural olive branches in Romans 11. Remember, not all of the natural olive branches are pruned out of the tree (which itself is not a reference to Israel, by the way, since Israel is only the cultivated, natural branches of the tree, not the whole tree itself) in that figurative explanation of present and future events, but rather some remained attached to the tree while the wild olive branches (referring to those of the nations) were grafted into the tree next to believing Israel/the Israel of God rather than replacing them, and we also know that the pruned-off natural branches will be grafted back into the tree eventually as well (this will occur at the time the wild branches are removed from the tree — if this seems confusing, it helps to understand that this passage has nothing to do with the salvation of individuals or the idea of losing salvation, which is made clear by the fact that the pruned-off natural branches were never saved to begin with and yet had to have been a part of the tree at one time in order to be pruned from it, and so if being a part of the tree means being saved, they never could have been a part of the tree in the first place). As Paul makes clear, Israel is not thrust away, but is only temporarily cast away until the full complement of the nations may be entering, at which point Israel will become the focus of God’s purposes again (since His promises and gifts are without repentance, which means it goes without saying that Israel will indeed be brought to faith and be saved in the end).
So, no, the body of Christ has not been subsumed into Israel, or even replaced Israel, and is not now “spiritual Israel” as some like to claim. Aside from the scriptural proofs I’ve already given above, that this isn’t the case is made obvious right from the beginning of the table of comparisons below, where we can see that Israel will still follow the law when the New Covenant comes fully into effect, whereas Paul went to great pains in his writings to explain that those of us in the body of Christ are not under the law, nor should we be trying to follow the law, and, in fact, we are not to allow ourselves to be placed under it in any way whatsoever.
The fact of the matter is, nowhere in Scripture is the body of Christ referred to as Israel, so to conflate the two of them requires one to read a preexisting bias towards the idea that they are one and the same into the various passages referring to Israel (not to mention the passages referring to Judah, which raises other questions such as, if the references to Israel in prophecy are actually a reference to the body of Christ, who or what is “Judah,” which is listed as a different group from Israel, in these prophecies a reference to?), but there’s no scriptural basis for doing so that I’ve ever seen (and believe me, I’ve looked, studying the Amillennialism perspective on this in order to see if they might have any plausible or convincing arguments for their position, but thus far, all of the attempts I’ve seen to reinterpret the Israel passages as referring to the body of Christ have been found severely wanting, which is almost certainly because those who have tried to do so in the past — at least all the Amillennialist theologians I’ve read — don’t seem to have been familiar with the “Concordant” interpretations which perfectly resolve the scriptural difficulties Amillennialists have with Dispensationalist Premillennialism). This means the default position has to remain that Israel is still Israel (even if not all ethnic Israelites are currently members of the Israel of God; and it should be noted that Paul was reducing the scope of the Israel of God there, not expanding it, since, although there might be the odd Gentile proselyte such as Cornelius and his family joining it — presuming his family wasn’t simply an example of how members of the nations will be saved by Israelites during the Millennium — members of the Israel of God will still primarily be Israelites), and the body of Christ is an entirely separate entity from Israel altogether (which, just as an aside, is also the position that was held to by pretty much by all Christians for the first few centuries of Christendom, until Augustine went and changed that fact; and while those of us in the body of Christ today don’t necessarily base our theology on what Christians have historically considered to fall under the purview of “orthodoxy” or “orthopraxy,” this is still a fact that those who are considering the topic should be aware of).
So, with all that in mind, let’s compare some of the teachings given to and about the Israel of God in the Circumcision writings (meaning the books of the Bible not signed by Paul) to the teachings given to and about the body of Christ by Paul, which should reveal a clear pattern of differences between the two sets of teachings, demonstrating not only the significant difference between the two churches, but also that the requirements for (or method of) salvation for both is somewhat different for each (which is why it is said that there are two Gospels, known as the Gospel of the Circumcision and the Gospel of the Uncircumcision), and that what their respective salvations consist of is different as well.
|The Israel of God/The Gospel of the Circumcision||The body of Christ/The Gospel of the Uncircumcision|
|Will keep the law perfectly when the New Covenant finally comes fully into effect and replaces the Old Covenant completely (Jeremiah 31:31-34, Ezekiel 36:26–27, Micah 4:2, Hebrews 8:8-12)||Not only are we not under the law at all, and in fact should not try to keep any of it (Romans 6:14, Galatians 5:3), Gentiles were never under the Old Covenant — which was about keeping the Mosaic law — to begin with, so we don’t have an Old Covenant to be replaced with by a New Covenant the way Israel does anyway (Romans 2:14-15, Ephesians 2:12)|
|Jewish believers within this church were still zealous for the law, even after the Council of Jerusalem, and they were upset that Paul was teaching Jewish members of the body of Christ to avoid practicing the Mosaic law, including circumcising (Acts 21:17-26)||Not only did Paul teach against circumcising — or any law-keeping — for Gentiles in the body of Christ, he taught against it for anyone in the body of Christ, including Jewish members, and if Paul was teaching the same thing that Peter and James and the rest of the Jewish church were, the members of their church in Jerusalem wouldn’t have been so upset at Paul for teaching against circumcising and law-keeping for Jewish members of his church when he visited them later (Acts 15:1-21, Galatians 2:1-3, Acts 21:17-26)|
|Spoken of by the prophets since the world began (Acts 3:21-25)||A secret until Paul (Romans 16:25, Ephesians 3:8-10)|
|Only 12 apostles for this church — a number with much spiritual significance to Israelites — and they were all called inside of Israel (Matthew 4:18-22, Matthew 10:2-4). Even though Judas was replaced by Matthias after being disqualified (Acts 1:12-26), no others out of the 12 were ever replaced because there will only be 12 thrones for them to sit on during the Millennium, and only 12 foundations of the wall of the New Jerusalem to be named after them during the Eon of the Eons (Matthew 19:28, Revelation 21:14)||The first apostle of our church — who is not one of the 12 apostles of the Israel of God — was called outside of Israel (Acts 9:3). This is spiritually significant because Paul was the apostle to the Gentiles (Romans 11:13)|
|Are supposed to eventually disciple all the nations, to baptize them into the name of the Father and of the Son and of the Holy Spirit, and to teach them to obey everything Jesus commanded (Matthew 28:16-20), although — outside of Peter’s visit to Cornelius —this hasn’t happened yet (Acts 11:19, Galatians 2:8-9)||The fact that Paul is called the apostle to the Gentiles, and that a whole new set of apostles were in fact sent to the Gentiles, is significant because it means the 12 apostles of the Israel of God were not the apostles to the Gentiles (Romans 11:13, Acts 14:14, 1 Corinthians 4:6-9, Ephesians 4:11), nor were the rest of the members that church preaching to the Gentiles yet either, since the pillars of their church had agreed to leave the preaching to the Gentiles to Paul and to those with him, for the time being, which means Israel hasn’t even really begun her so-called “Great Commission,” as it’s often referred to (Galatians 2:8-9, Acts 13:2)|
|Proclaimed among Israelites (James 1:1, 1 Peter 1:1)||Proclaimed among the Gentiles (Ephesians 3:8)|
|Saints termed the bride of the lambkin (John 3:29, Revelation 21:9)||Saints termed the body of Christ (Ephesians 5:30)|
|Racial distinctions important (Matthew 15:26, Matthew 19:28, Revelation 21:12, Zechariah 8:23)||Racial distinctions irrelevant (1 Corinthians 12:13, Galatians 3:28)|
|Believers known from the disruption of the world (Revelation 17:8)||Believers known before the disruption of the world (Ephesians 1:4)|
|Believers called first, then chosen (Matthew 22:14)||Believers chosen first, then called (Romans 8:30)|
|Water baptism required (Acts 2:38)||Water baptism not required (1 Corinthians 1:17, 1 Corinthians 12:13)|
|Many types of baptism/immersion: John’s baptism in water unto repentance, the Lord’s baptism in water — obviously not a baptism unto repentance — water baptism in the name of Jesus Christ/the name of the Lord, baptism in the Holy Spirit, and in fire, baptism into Moses, and baptism into the name of the Father and of the Son and of the Holy Spirit (Matthew 3:11, 13-17, Acts 1:4-5, Acts 2:38, Acts 10:48, 1 Corinthians 10:2, Matthew 28:19)||Only one baptism/immersion: by the Holy Spirit into the body of Christ, including into what He experienced in His body, such as His death (Ephesians 4:5, 1 Corinthians 12:13, Romans 6:3-4)|
|Must be born again (John 3:3)||Are an entirely new creation (2 Corinthians 5:17)|
|Must have circumcision of the heart (Deuteronomy 10:16, Acts 7:51, Romans 2:29)||Circumcised of the body of flesh in the circumcision of Christ (Colossians 2:11)|
|Must have works, since faith without works is dead for them (James 2:20)||Even if we don’t have works, but only have faith, we are still justified, which means faith without works is not dead for us (Romans 4:5)|
|Must keep His commandments, and live as Jesus did (1 John 2:3-6)||God’s grace motivates us to live well, not the threat of losing our salvation if we don’t, as is the case for Israel (2 Corinthians 5:14-15)|
|Must forgive others or God will not forgive them (Matthew 6:15)||Should deal graciously with others as God has already dealt graciously with us (Ephesians 4:32) — but even without works, we’re still justified, so we aren’t required to forgive others in order to be forgiven ourselves, even if it’s still good for us to do so (Romans 4:5)|
|Must be an overcomer to avoid second death (Revelation 2:11)||Saved from second death by grace alone (Ephesians 2:8-9)|
|Hoping for grace, which will be brought to them when Jesus returns to the earth (1 Peter 1:13)||Already standing in grace (Romans 5:2)|
|Must be watching (Luke 12:37, Hebrews 9:28)||Whether watching or drowsing (1 Thessalonians 5:10)|
|Can be put to shame at His presence (1 John 2:28)||Will be changed at His presence (1 Thessalonians 4:15-17, 1 Corinthians 15:52)|
|Will go through day of indignation (Revelation 7:1-17)||Not appointed to indignation (1 Thessalonians 1:10, 1 Thessalonians 5:9)|
|Will meet Christ on earth (Acts 1:11-12, Zechariah 14:4)||Will meet Christ in the air (1 Thessalonians 4:16-17)|
|The resurrection of the just, also known as “the former resurrection” (Luke 14:14, Revelation 20:1-6), occurs after Christ’s second coming to the earth, 75 days after His feet touch down on the Mount of Olives (Zechariah 14:4-7, Acts 1:9-12, and compare the numbers in Daniel 12:11-13 to the numbers in Revelation 13:5 to understand the 75 day difference)||The dead in the body of Christ are first resurrected, then those who are still living will rise with them to meet Christ in the air together when He comes for our church, before He ever even touches down on the Mount of Olives (1 Thessalonians 4:16-17)|
|Will reign on the earth as a kingdom of priests over the nations (1 Peter 2:5-9, Revelation 2:26-27, Revelation 5:10, Revelation 20:6, Isaiah 61:6)||Will reign among the celestials in the heavens (Ephesians 2:6-7, 2 Timothy 2:12)|
|Will fill earth with knowledge of God’s glory by being a light to the Gentiles and salvation to the ends of the earth (Habakkuk 2:14, Isaiah 49:6)||Will dispense God’s wisdom among the celestials in the heavens (Ephesians 3:10-11)|
|The meek shall inherit the earth, and will live in the land God gave the patriarchs, which is the land of Israel (Matthew 5:5, Ezekiel 36:28)||Our realm is inherent in the heavens (Philippians 3:20)|
|There will still be mortal “flesh and blood” humans living in the part of the Kingdom of God that is on the earth, and they will even continue to reproduce, during both the Millennium and the Eon of the Eons (Zechariah 8:3-4, Isaiah 65:17-25, Ephesians 3:21)||Mortal “flesh and blood” is not able to enjoy the allotment in the part of the Kingdom of God that is in the heavens. This is simply because we’d suffocate from lack of oxygen, or freeze to death, or die from radiation poisoning out there in the heavens without an immortal body (1 Corinthians 15:50-54)|
|The 12 apostles will judge the 12 tribes of Israel (Matthew 19:28)||Paul, not one of the 12 apostles of the church known as the Israel of God, but rather the first apostle of the church known as the body of Christ, will, along with the rest of the body, judge the whole world — presumably at the Great White Throne Judgement; based on how long it would take one Person to judge everyone on His own, Jesus will need a whole group of people to dispense this judgement, since it takes place on earth among the resurrected dead, not outside of time — as well as judge angels (1 Corinthians 6:2-3)|
|Their Gospel is also called the Gospel of the Kingdom, and it was the Good News that the Kingdom of God was near, meaning ready to begin if Israel met the required conditions (Mark 1:14-15), which they did not, so its fully coming into effect on earth — specifically in Israel — has been pushed back while the Gentiles are temporarily saved apart from Israel (Acts 28:17-28, Romans 11)||Our Gospel was also called “my Gospel” by Paul, which is why we now call it Paul’s Gospel, and it’s simply the Good News that Christ died for our sins, that He was entombed, and that He was roused the third day (Romans 2:16, Romans 16:25, 2 Timothy 2:8, 1 Corinthians 15:1-4)|
|Had to believe that Jesus is Israel’s awaited Messiah, and the Son of God, as well as follow it up with baptism and other good works such as forgiving others, and even endure to the end — of their life or of the Tribulation, whichever comes first — in order to be saved under this Gospel, although this is only salvation from a relative perspective (John 20:31, Acts 2:38, Acts 8:36-38, Matthew 3:8, Matthew 6:15, Matthew 24:13). The 12 did not understand that Jesus was going to die, so they couldn’t have been preaching anything related to Paul’s Gospel about Christ’s death for our sins when Jesus sent them to preach the Gospel of the Kingdom while He walked the earth (Luke 18:31-34, Matthew 10:5-7, 22)||Said to be saved simply by believing — which includes understanding what it means — that Christ died for our sins, that He was entombed, and that He was roused the third day (1 Corinthians 15:1-4), although this is only salvation from a relative perspective, since all humanity is guaranteed salvation from an absolute perspective because of what Paul’s Gospel means, even if those who believe this Gospel now get a special, early experience of salvation before everyone else (1 Corinthians 15:22-28, 1 Timothy 4:10)|
|The cross was only bad news to those hearing the Gospel of the Kingdom — at least in the sermons recorded in Acts— and a shameful thing which needed to be repented of in order to be saved (Acts 2:22-38, Acts 3:13-15, Acts 7:52)||The cross is only Good News for those hearing Paul’s Gospel, and is even something to glory in because it is how we are saved (1 Corinthians 1:18, 1 Corinthians 15:1-4, Galatians 6:14)|
|From a relative perspective, Jesus gave His life as a ransom only for “many” — meaning only for those who obey this Gospel (Matthew 20:28)||From an absolute perspective, Jesus gave His life as a ransom for all — meaning all humanity (1 Timothy 2:6)|
|Exhorted to remain in Him, and seem to be able to fall away and not be able to be renewed to repentance, so seem to be able to lose their sort of salvation (1 John 2:28, Hebrews 6:4-6, Hebrews 10:26-27), although this is only salvation from a relative perspective, and anyone who doesn’t experience this sort of salvation will still eventually experience the salvation of Paul’s Gospel from an absolute perspective||If we died with Him — and if we did, we can’t un-die — we will live with Him, since He cannot disown His own body. Yes, we can “fall from grace,” so to speak — which basically just means placing oneself under the bondage of religion and rules, such as the law, and, because of doing so, missing out on enjoying the freedom Christ gave us — and we can also lose out on reigning with Him by denying Him in order to avoid suffering, but we still remain His body, and He won’t amputate and disown His own body parts, and body parts can’t amputate themselves either (Galatians 5:1-4, 2 Timothy 2:11-13)|
|Abraham being justified by works given as an example (James 2:21-23)||Abraham being justified by faith rather than by works given as an example (Romans 4:2-3)|
|Gentiles will be blessed by Israel’s rise in the future (Acts 3:25)||Gentiles are currently blessed by Israel’s fall (Romans 11:11)|
|Salvation will come in the future, when the Kingdom comes fully to the earth, and when Israel’s sins are forgiven (1 Peter 1:5, Romans 11:25-27)||We have already been saved now, and are, in fact, already complete in Christ (Ephesians 1:13, Colossians 2:10)|
|Healing others by the laying on of hands is a sign that will accompany believing members of this church, and members are advised to go to the elders for prayer and anointing with oil for their own healing (Mark 16:18, James 5:13-18)||While Paul could heal people by having them simply touch his handkerchiefs at the beginning of his ministry, when he was still trying to convince Israelites to believe their own Gospel, by the end of his ministry, after giving up on Israel for the time being and deciding to only proclaim his own Gospel to the nations, he could no longer heal, and even gave medicinal advise to church members rather than advising them to seek healing from church elders (Acts 19:12, 1 Timothy 5:23, 2 Timothy 4:20)|
I could go on and on, but if that isn’t enough to prove the point to someone, I don’t know what will be. The above reveals a clear pattern of significant differences between the Israel of God and the body of Christ (as well as between their two Gospels and what their respective salvations entail), and if someone still can’t see the differences after reading that, I’m not sure there’s any hope left for them (at least in this eon), because these aren’t just minor variations in terminology; these are quite obviously completely different sets of information regarding two completely different groups of people.
Unfortunately, if one isn’t being honest with Scripture and insists on trying to make these major differences between Paul’s teachings to the body of Christ and the teachings in the Circumcision writings say the same thing because their preconceived doctrinal biases force them to have to believe they mean the same thing, they’re just not ready to interpret the rest of Scripture. In fact, not only is this concept so extremely important for believers to grasp, it’s also so central to understanding what the Bible is saying that one can’t properly interpret much of Scripture at all without beginning from this perspective. So I pray that the above has made the differences clear to you. Whether they have or not, though, I go into more detail on this in chapter 1 of my eBook, which is available for free here on this website, so I recommend checking it out for a deeper understanding of the things that differ.