Yahshua was commissioned for none but Israel. YHWH's renewed covenant is with Israel.
The same could be said of the "New Covenant" Jer 31:31-34, Heb 8:6-12.
So you make a very good point in that regard.
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But there is always the Rom 2 as a qualifier for gentiles in certain cases.
Rom 2:28 For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh. 29 But he is a Jew who is one inwardly; and circumcision is of the heart, by the Spirit, not by the letter; and his praise is not from people, but from God.
In Acts 21 we see gentiles exempted from part of the law - (ceremonial) -- which is not possible at all if there is only two groups - namely "saved vs lost" or put another way -- "Jew vs gentile".
Acts 21:
20 And when they heard
about them, they
began glorifying God; and they said to him, “You see, brother, how many thousands there are among the Jews of those who have believed, and they are all zealous for the Law; 21 and
they have been told about you, that you are teaching all the Jews who are among the Gentiles to abandon Moses, telling them not to circumcise their children nor to walk according to the customs. 22 So what is
to be done? They will certainly hear that you have come. 23 Therefore, do as we tell you: we have four men who have a vow upon themselves; 24 take them along and purify yourself together with them, and pay their expenses so that they may shave their heads; and
then everyone will know that there is nothing to what they have been told about you, but that you yourself also conform, keeping the Law. 25
But regarding the Gentiles who have believed, we sent a letter, having decided that they should abstain from meat sacrificed to idols and from blood and what is strangled, and from sexual immorality.” 26 Then Paul took along the men, and the next day, after purifying himself together with them, he went into the temple giving notice of the completion of the days of purification, until the sacrifice was offered for each one of them.
It is very clear in that chapter that they were not telling gentiles to participate in temple ritual washings/vows./circumcision etc Distinctions between Jewish Christians and Gentile Christians existed at least at some level - in terms of practice -- according to Acts 21.
In Acts 21 - the Church leaders in Jerusalem want Paul to participate in a temple ritual that was very distinctly applicable to the Jewish |Christians and not the Gentiles - as proof that he was not teaching Jewish converts to do the very thing he was being accused of before the Christian Jewish leadership in Jerusalem.