Your explanation - that Paul used the singular word “gospel” because he was speaking only TO the Galatians about their “Gentile Gospel” - would satisfy only someone who had already made up their mind about it. It is a weak argument for anyone outside the “dual gospel” camp. All it amounts to is an attempt to explain the lack of supporting evidence in the passage. It is not a direct appeal to contextual evidence in the passage. When the actual words that are used here and elsewhere are considered, a different meaning emerges.
6 I am astonished that you are so quickly deserting him who called you in the grace of Christ and are turning to a different (heteros) gospel— 7 not that there is another, (allos) one but there are some who trouble you and want to distort THE Gospel of Christ (Galatians 1:6-7 ESV).
Paul uses the singular form of the word “Gospel” adding that the Judaeizers were attempting to distort this message thereby turning it into a “different” (false) gospel. Only the gospel as he originally delivered to them could save them. He neglected to say there was yet another valid gospel. You say he just did not bring it up. The telling point is that he did not bring it up at any other time either.
Let us assume for the sake of argument that there were two gospels. First, Jewish as well as Gentile believers were living in the region of Galatia. This can be seen by internal evidence in their knowledge about the Law by also external historical evidence. The Jewish believers presumably would have been following the teachings of the “Jewish Gospel” which Paul knew very well since it was his custom to peach that message in the synagogues every Sabbath
If Jewish believers were in there would it not have been necessary to help them differentiate their Jewish Gospel which COULD save from the message of the Judaeizers which could NOT? It seems to me that the Christian Jews would have been even more tempted by the Judaizer’s teaching than the Gentiles. This would have been the perfect occasion to lay out exactly what the two gospels were in unambiguous language but Paul, the “wise master builder.” leaves this vital issue unresolved though it could have caused apostasy and Church fragmentation. This would have been an important point to make in any Church where the Judaizers were a threat.
If MAD is true then Paul consistently neglected to teach on the nature of the Jewish Gospel comparing and contrasting it to the Gentile Gospel. He does not even use the plural of "Gospel" At least with Baptism, while one scripture seems to indicate that there is only one (Ephesians 4:5) others go on to explain the different "baptisms" in unambiguous terms (e.g., Matthew 3:11). The Bible also establishes a plurality of Baptisms through using the plural form of the noun “baptism.” (Hebrews 6:2). There is no need to read between the lines to see that there is more than one baptism.
Yet, to what passage shall we turn to see a comparison and contrast of the Gospels of the Jews versus that of the Gentiles? Despite the supposed importance of making a distinction between the two, the Bible does not address this very important matter. Instead we are left to come to that conclusion through inferences and assumptions.
What the Bible EXPLICITLY says about the Gospel is not hard to discern, so long as we accept prima fascia what the passage says and avoid importing ideas from outside the text.
For I am not ashamed of THE gospel, for it is THE power of God for salvation to everyone who believes, to the Jew first and also to the Greek. 17 For in IT the righteousness of God is revealed from faith for faith, as it is written, “The righteous shall live by faith.”(Romans 1:16 ESV)
Here Paul speaks of a singular gospel but contrary to your claim in Galatians - that when he used the singular of "Gospel" he meant only the Gentile Gospel - here he says that THE Gospel is invested with THE power to save both Jew and Gentile. Two gospels need not be preached. One was sufficient for both.
Here is another passage:
18 For THE WORD of the cross is folly to those who are perishing, but to us who are being saved it is THE power of God…22 For Jews demand signs and Greeks seek wisdom, 23 but we preach Christ crucified, a stumbling block to Jews and folly to Gentiles, 24 but to those who are called, both Jews and Greeks, Christ THE power of God and THE wisdom of God. (Ephesians 1:18,22-24)
THE WORD of the cross is the same as THE PREACHING of the cross or the Message of the Cross all of which are equivalent to the Gospel of the Cross. As with the previous scriptures I have cited, THE WORD, is written in the singular form meaning that there is one. You can parenthetically say "not including the Jewish Gospel" but this is what the text says. This single message is invested with THE power to save BOTH Jew and Gentile. No other special gospels are needed. Paul did not even try to adapt his message to suit the Jews and Gentiles though the one message was a stumbling block to both.
Lastly, I do not know how you can say I made up anything since my conclusion was based, not on my personal opinion but on linguistic data and historical sources (which I cited). You are free to deny it, of course, but a denial is not a rebuttal and unless you can add something of substance I am going to take what you said as a gratuitous assertion. I will come back to this issue soon.
Paul was saved and called into that gospel of [concerning] Christ that he preached after Israel's fall.
In Galatians 2:2, he refers to it as "that gospel which I preach among the Gentiles."
In 2:7, he refers to it as "the gospel of the uncircumcision."
And in 2:8, he relates that his Apostleship was the Apostleship of the Gentiles [the uncircumcision].
In 2:9, he agrees to confine his preaching "unto the heathen."
Bear with me a moment...
This Gospel of Christ = that gospel which I preach among the Gentiles = the gospel of the uncircumcision = unto the heathen.
The key is in identifying who these Gentiles; these Uncircumcision; these Heathen, are.
Paul entered into that agreement way before he later wrote Romans 1: 17's "to the Jews first..."
Further, Paul is depicted going to the Jew from Acts 9 when he was saved, to the very last chapter of Acts.
What about this agreement he'd entered into with James; Cephas and John years before Acts 28 - that he would go unto the heathen, and they would go unto the uncircumcision?
Therein lies the answer to this two gospel assertion we of Mid-Acts hold to [though we differ with one another within Mid-Acts as to some of the particulars, neverthless we do hold to this much about this issue].
In Matthew 10, the Lord foretells the persecution the Twelve will undergo in what will later be depicted by Luke in Acts 4 thru 7.
He also tells them they will not make past the cities of Israel with "the gospel of the kingdom... the lost sheep of the house of Israel," before His return, Matt. 10:5-6; Matt. 10:23.
Then, in Matthew 12 He warns Israel as to the following [see also, Hebrews 2]:
30. He that is not with me is against me; and he that gathereth not with me scattereth abroad.
31. Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men.
32. And whosoever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come.
33. Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit.
34. O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.
In Acts 7, the height of Israel's persecution against them culminates in the following pronouncement by the Spirit speaking through Stephen just before they murder him:
51. Ye stiffnecked and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers did, so do ye.
52. Which of the prophets have not your fathers persecuted? and they have slain them which shewed before of the coming of the Just One; of whom ye have been now the betrayers and murderers:
53. Who have received the law by the disposition of angels, and have not kept it.
54. When they heard these things, they were cut to the heart, and they gnashed on him with their teeth.
Years later, Paul will note in Romans 2, as he begins to there lay out the theme he will later expand on in Romans 9 thru 11 - why God turned from Israel [albeit, temporarily, Rom. 11:25-29].
Note what he says in Romans 2 - it fist what the Spirit declared thru Stephen:
23. Thou that makest thy boast of the law, through breaking the law dishonourest thou God?
24. For the name of God is blasphemed among the Gentiles through you, as it is written.
25. For circumcision verily profiteth, if thou keep the law: but if thou be a breaker of the law, thy circumcision is made uncircumcision.
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.
Note how that the Lord made this very same point as to this Law keeping of the heart - John 5:
44. How can ye believe, which receive honour one of another, and seek not the honour that cometh from God only?
45. Do not think that I will accuse you to the Father: there is one that accuseth you, even Moses, in whom ye trust.
46. For had ye believed Moses, ye would have believed me; for he wrote of me.
47. But if ye believe not his writings, how shall ye believe my words?
In other words, theirs was outward law keeping. In this they failed to keep the Law they only appeared to be keeping before one another.
In other words - in Acts 7 Israel was concluded uncircumcision - just another lost, Gentile nation - heathen!
Romans 11:
7. What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.
Cut off from "the gospel of the kingdom" the Twelve were never able to reach all the lost sheep of the house of Israel with before the Lord's return!
Their aspect of the gospel of Christ - the gospel of the circumcision - Acts 3:
17. And now, brethren, I wot that through ignorance ye did it, as did also your rulers.
18. But those things, which God before had shewed by the mouth of all his prophets, that Christ should suffer, he hath so fulfilled.
19. Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord.
20. And he shall send Jesus Christ, which before was preached unto you:
21. Whom the heaven must receive until the times of restitution of all things, which God hath spoken by the mouth of all his holy prophets since the world began.
22. For Moses truly said unto the fathers, A prophet shall the Lord your God raise up unto you of your brethren, like unto me; him shall ye hear in all things whatsoever he shall say unto you.
But as Paul would later relate as to that in light of Acts 7...
Romans 11:
7. What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.
Now, the only chance they had was this gospel of the uncircumcision God was now having preached among the Gentiles - as is the case today. Today, if a Jew wants salvation, he has to forgo his tradition, make like a Gentile, and trust this gospel of the uncircumcision, because that is what the Spirit concluded that nation - "uncircumcised in heart and ears."
In this, it is not strange at all then, that in Acts 21, James relates to Paul their having heard he has dropped the circumcision requirement among those Jews in his ministry.
As for James, Cephas and John, after all this; they agree to confine their ministry, not as per the Matthew 28 "all nations" commission, rather "unto the circumcision."
Hunh?
A passage like Acts 10:45 identifies those as "they of the circumcision which believed." Acts 11: 2 refers to them as "they that were of the circumcision."
That is a reference to they of the circumcision which believed before Israel was cut off - Romans 11: 7. What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.
Hebrews thru Revelation speaks to these of the circumcision which believed, before Israel fell, at Acts 7.
Romans thru Philemon speaks to uncircumcision Jew and Gentile after Israel's fall; Romans 3.
Now, here is an interesting question - why then do we read in Acts 11:19 "Now they which were scattered abroad upon the persecution that arose about Stephen [back I Acts 8] travelled as far as Phenice, and Cyprus, and Antioch, preaching the word to none but unto the Jews only" ?
And why have there numbers grown into "many thousands of Jews there are which believe; and they are all zealous of the law" by Acts 21:20?