There is only one Gospel, for Jews and non-Jews.
I am a Hebrew Catholic, of Sephardic Jewish lineage. As such I take the words of the Apostle Paul as my own to declare: “We, who are Jews by nature and not [so-called] sinners from among the Gentiles, yet who know that a person is not justified by works of the law but through faith in Jesus Christ, even we have believed in Christ Jesus that we may be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified.”–Galatians 2:15-16.
Now, it is true that the way the Gospel is preached and practiced differs between Gentile and Jew. (Galatians 2:7-9) As a recent document released from the Vatican on this subject points out, the covenant between the Jews and God is irrevocable and still in effect. The Apostles knew this, and when Paul’s ministry to the Gentiles announced that Gentiles were not obliged to follow the Mosaic Law, both parties agreed that Paul’s arguments were with the exception of Jewish Christians who were Torah-observant. (Acts 21:17-26) The call to faith in Christ does not include a demand for anyone to disown their culture and traditions, merely to live them in the light of Christ. This stands not only for Gentiles whose customs are inherited from the heathens and pagans, but for Jews whose customs and traditions come from the Law of Moses. Except for that which conflicts with the Gospel, God has come to preserve all peoples and their rich diversity.
The Mosaic Law does not promise a way to make the one who obeys it justified for eternal life. Only the grace of God by means of faith in Jesus can do that. But, as the Apostles noted as mentioned above in Acts chapter 21, Christians of Jewish ancestry have only one culture to live based on the Mosaic Law. As long as a Christian Jew does not make the claim that their obedience to the Law or any custom that is based from it is a requisite to gaining salvation, the Jew who accepts Jesus of Nazareth as Messiah is no more obligated to abandon their way of life anymore than a Gentile is obligated to leave their secular and pagan-based cultures to embrace that of the Jews.
This was the only the reason for a ministry to the Jews under St. Peter and the ministry to the Gentiles given to St. Paul. The Gospel message being universal requires adjustment to show how it applies to each and every culture and peoples that it comes to.(1 Corinthians 9:19-23) But the Gospel message and the way to salvation is but one, Jesus.–John 14:6.