After doing a little research, I think I understand more fully what you are saying here, though, again, I disagree with your conclusions.
The New Covenant which Jesus institutes was not a complete break from the old, but a perfecting of it. And the gospel of grace I think is the message that the grace which was first given to the Jews is now poured out for all who believe in Jesus Christ.
Where before, those who were Jewish were born into the covenant by virtue of their race, now we are all adopted by virtue of our belief in the saving grace of the sacrifice of Jesus Christ.
The good news is the same for both Jews and Gentiles then.
It is that through Jesus, we are all God’s children, heirs to the Kingdom. We, though not of Jewish birth are a new branch of the vine which is Jesus, who because He is eternal is the same yesterday, today and tomorrow.
I believe what I said in my previous post regarding Paul and his relationship to the others and to the gospel.
What you write is interesting, and I see that many people believe it, but I am not one of them, because I believe that the progressive revelations of God were meant to unite all His people.
The Apostle Paul was given a gospel to preach by direct revelation of Jesus Christ. He called it "MY GOSPEL". It IS the gospel that WILL be used by God to judge men by Jesus Christ.
We have talked about and listed all the gospels in the Bible. The hope I have for you is that you find the gospel that was given to Paul. It IS the one that is going to be used by God. That is, according to God. God Bless, smvoice