Paul's summary of "his" gospel in 1 Cor 15 includes the Galilean apostles and so forth.
By all accounts, the gospel Paul preached looks like the one Peter preached. Peter even calls Paul's letters "scripture".
That might be more true if Peter hadn't been acknowledged as the author of the Gospel called Mark. The first words of this Gospel says it's the Gospel of the Kingdom of God. Our Peter would've had to be a newbie to call the things done on the cross the whole Gospel.
Peter
translated by Mark 1:14-15 Now after that John was put in prison, Jesus came into Galilee, preaching the Gospel of the Kingdom of God, And saying, The time is fulfilled, and the Kingdom of God is at hand: repent ye, and believe the Gospel.
Matthew 5:19 Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach [them], the same shall be called great in the Kingdom of Heaven.
John 14:15 If ye love Me, keep My commandments.
Versus
Ephesians 2:8-9 For by grace are ye saved through faith; and that not of yourselves: [it is] the gift of God: Not of works, lest any man should boast.
1 Corinthians 2:2 For I determined not to know any thing among you, save Jesus Christ, and him crucified.
Colossians 2:14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;
It seems to me you are trying to create a separation between Paul's teachings and the Galileans based on Paul's phrase "my gospel" - as if this phrase could only have one possible meaning.
But Paul didn't quote the Kingdom Gospel... I can't find him doing it.
Where'd you find the Sermon on the Mount in Pauline Doctrine?
And if he uses the phrases therein, why not give direct quotes?
What about Galatians 2:7-9 ? Want to make that a metaphor/myth?
The proof of this is all over the scriptures. Jesus repeatedly told the Jews that the nations would also receive the promise, and if the jews rejected it, they would be shut out. Then in Acts, the Holy Spirit gift of tongues is a sign that what the Galilean apostles recieved from Christ, the apostles who received the Spirit first, was for all the nations. In Acts 1, Jesus explicitly links the coming of the Kingdom with the giving of the Spirit. So we know that whoever has the Spirit has the Kingdom. (In the Gospel accounts, there are many times Jesus makes this link.) Then that same Spirit is poured out over Gentiles freely - Gentiles who did not obey the Law.
To make that statement, you had to completely disreguard what the Kingdom Gospel says about the Holy Spirit. Like everything else within the Kingdom Gospel, there are requirements.
If you keep Jesus' commandments,
then the Father will give you the Holy Spirit... just as it was in the Old Testament.
John 14:15 If ye love Me, keep My commandments. 16 And I will pray the Father, and He shall give you another Comforter, that He may abide with you for ever; 17 [Even] the Spirit of truth; whom the world cannot receive, because it seeth Him not, neither knoweth Him: but ye know Him; for He dwelleth with you, and shall be in you. … 26 But the Comforter, [which is] the Holy Ghost, whom the Father will send in My name, He shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.
If you were with Jesus from the beginning,
then you will be His witnesses.
John 15:26 But when the Comforter is come, whom I will send unto you from the Father, [even] the Spirit of truth, which proceedeth from the Father, He shall testify of Me: 27 And ye also shall bear witness, because ye have been with Me from the beginning.
What the Holy Spirit does, according to the Kingdom Gospel.
John 16:7 Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send Him unto you. 8 And when He is come, He will reprove the world of sin, and of righteousness, and of judgment: 9 Of sin, because they believe not on Me; 10 Of righteousness, because I go to My Father, and ye see Me no more; 11 Of judgment, because the prince of this world is judged. 12 I have yet many things to say unto you, but ye cannot bear them now. 13 Howbeit when He, the Spirit of truth, is come, He will guide you into all truth: for He shall not speak of Himself; but whatsoever He shall hear, [that] shall He speak: and He will shew you things to come. 14 He shall glorify Me: for He shall receive of Mine, and shall shew [it] unto you. 15 All things that the Father hath are Mine: therefore said I, that He shall take of Mine, and shall shew [it] unto you.
The giving of the Holy Spirit to the Galilean Apostles.
John 20:21 Then said Jesus to them again, Peace [be] unto you: as [My] Father hath sent Me, even so send I you. 22 And when He had said this, He breathed on [them], and saith unto them, Receive ye the Holy Ghost: 23 Whose soever sins ye remit, they are remitted unto them; [and] whose soever [sins] ye retain, they are retained.
How did they receive the promise of Jesus, the Kingdom, the Spirit, without obeying the Law? This is the question the Galileans grapple with, and their conclusion is simple: the Kingdom is for all in Christ, Jew and Gentle. Peter reiterates this teaching in 1 Peter, calling both the Jews and the Gentiles a chosen nation, a royal priesthood.
The narrative throughout the NT is clear. Jesus is the saviour of all men, and the Kingdom is a Kingdom for the nations.
Paul receives a mission from Christ to go the Gentiles, but even right at the end of the book of Acts we see him trying to convince Jews. Why would he do that unless "his" gospel was also for them? Why did God send Peter to Cornelius and have those Gentiles saved by Peter's gospel, if Peter's gospel was not also for them?
Both Paul and Peter and John clearly see a vision of all the nations being one Church, with one faith, one Messiah, one baptism, one Spirit, one body, one eschatological outcome, one Kingdom. Any theology contrary to this is creating division where there should not be, and is dreaming up separation where there is none.
Matthew 5:17-18 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.
Now, "If ye love Me keep My commandments" is pretty much the centerpiece
(IMO) of the entire Kingdom Gospel.
But where do we even find the word "commandment" in the gospel to the gentiles, where it isn't being used as a curse word?
I kinda think Romans must Paul's gospel in a nutshell.
Romans 2:13 (For not the hearers of the law [are] just before God, but the doers of the law shall be justified.
What Paul calls a bad thing /\, Jesus calls life itself \/:
Matthew 7:24-25 Therefore whosoever heareth these sayings of Mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock.
How you reconcile these two things, must be like lawyers creating loopholes.
Jesus didn't send His Apostles from Galilee to the Judeans, He sent them to the lost sheep of the house of Israel. The kingdom is still divided, and the 10 tribes called Israel lived (those within Palestine, not those scattered among the nations) north of Samaria, while the nation called Judean was south of Samaria. Paul was part of the southern house, because Benjamin was given to Judah when the kingdom was divided.
I can't for the life of me understand why the Apostles of Galilee would have
wanted to walk in Jewry (when Jesus went out of His way to avoid it, and stay alive long enough to complete His mission)... with the weight of all of Matthew 23 and John 8 and the Revelation... they packed up and moved to the epicenter of the people who killed Jesus for His inheritance Matthew 21:38. Wait. What? That's the stuff of nightmares.