No, Paul did not talk about the unification of Jews and Gentiles into *one nation.* He spoke about their unification with respect to a unified membership in the Body of Christ. Christ is one, and those who become members in him are unified in him, and not in their differences.
It isn't the NT or the OT that divides the "many nations" from the "one nation," Israel. Rather, it was God's promise that those 2 elements *must* be in place. That doesn't change with the NT era. Those same 2 elements remain in play, because the fulfillment of these promises have not been completed yet.
That's why, in the book of Revelation, we see references to "many nations," to "Israel," because Abraham's promises are still being fulfilled. They aren't completed until they reach a place where their existence is no longer being threatened.
In the present age, Christian nations and Israel's status as a "nation of God" is constantly being threatened and hindered by Satan. When Satan is bound at the 2nd Coming of Christ, Israel will emerge, once again, as a godly nation. And many Christian nations will reassert themselves as such, without all of the compromise and corruption.
Rev 2.26 To the one who is victorious and does my will to the end, I will give authority over the nations.
10.11 Then I was told, “You must prophesy again about many peoples, nations, languages and kings.”
12.5 She gave birth to a son, a male child, who “will rule all the nations with an iron scepter.”
15.3 and sang the song of God’s servant Moses and of the Lamb: “Great and marvelous are your deeds, Lord God Almighty. Just and true are your ways, King of the nations...4 All nations will come and worship before you, for your righteous acts have been revealed.”
18.23 All nations will come and worship before you, for your righteous acts have been revealed.”
20.3 He threw him into the Abyss, and locked and sealed it over him, to keep him from deceiving the nations anymore until the thousand years were ended.
21.24 The nations will walk by its light, and the kings of the earth will bring their splendor into it... 26 The glory and honor of the nations will be brought into it.
22.2 And the leaves of the tree are for the healing of the nations.
Note that in ch. 20 the nations in the present age are in a state of being "deceived." They need to be "healed," according to ch. 22. God's plan is for Christ to rule the nations. That doesn't end at the 2nd Coming. It *begins* at the 2nd Coming, when the nations are no longer deceived, and are "healed!"
Our unity is in one man, who is divine--Christ. But our national and racial distinctions remain until our mortal existence ceases to be. According to the above Scripture passages, that will not happen until *after* Christ heals the nations and removes the one who is deceiving them, Satan. This will enable the fulfillment of God's promise to Abraham, to be the father of both Israel and many nations.
You're welcome to your own opinion. This is mine.
All promises are fulfilled and completed.
In God's New Will and Testament, all covenants and promises are fulfilled only in Christ, and in those who are in Christ.
The OT covenants and promises are the promissory clauses of God's Old Will and Testament, and they are both revoked and fulfilled in the promissory clauses of His New Will and Testament, written in the Blood of His Son Jesus Christ, the Divine Testator, coming into full force and effect upon His death.
If you have made your own Will and Testament, you will see that the very first clause states the following or its equivalent:
"I HEREBY REVOKE all former Wills and other testamentary dispositions by me at any time therefore made and declare this to be my Last Will and Testament."
This means that all former wills and testaments, and all of their promissory clauses in their entirety, are completely null and void. In their place, the promissory clauses of the current last new will and testament are the only ones in force and effect. Any promissory clause which appeared in the old will and testament, but does not appear in the new will and testament, is irrevocably null and void unless yet another new will and testament is made which re-includes it.
Thus we see:
Hebrews 9
15 And for this cause he is the
mediator of the new testament, that
by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.
16 For where a testament is, there must also of necessity be the
death of the testator.
17 For a
testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth.
Hebrews 10
9 Then said he, Lo, I come to do thy will, O God. He
taketh away the first, that he may establish the second.
Hebrews 8
13 In that he saith, A
new covenant, he hath
made the first old. Now that which decayeth and waxeth old is ready to
vanish away.
God`s New Will and Testament is everlasting:
Hebrews 13
20 Now the God of peace, that brought again from the dead our Lord Jesus, that great shepherd of the sheep, through the blood of the
everlasting covenant.
There is none greater.
We see other new promissory clauses of the New Will and Testament in:
Matthew 21:33-45
In this parable, the son, who is identified as the heir, typifies
Christ.
Galatians 3:16
Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is
Christ.
2 Corinthians 1:20
For all the promises of God in
him are yea, and in
him Amen, unto the glory of God by us.
Hebrews 1:1,2
1 God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets,
2 Hath in these last days spoken unto us by his
Son, whom he hath appointed
heir of all things, by whom also he made the worlds;
In them, we see that the Heir and Beneficiary is
Christ alone, that
all of the promises are affirmed and confirmed in Him, and that He is Heir of
all things.
All includes the OT
land promises, the
restoration promises, the
blessings promises, and
all else. There are
no exceptions.
If you deny that God has appointed His Son
heir of all things, you declare God to be a liar.
His New Will and Testament contains even better promises:
Hebrews 8
6 But now hath he obtained a
more excellent ministry, by how much also he is the mediator of a
better covenant, which was established upon
better promises.
Such as:
Hebrews 11
16 But now they desire a
better country, that is,
an heavenly: wherefore God is not ashamed to be called their God: for he hath
prepared for them a city.
Additional promissory clauses in...:
Romans 8:16-17
16 The Spirit itself beareth witness with our spirit, that
we are the
children of God:
17 And if children, then
heirs;
heirs of God, and
joint-heirs with
Christ; if so be that we suffer with him, that we may be also glorified together.
Galatians 3:29
And if ye be
Christ's, then are ye
Abraham's seed, and
heirs according to the promise.
...declare that we who are in Christ are joint heirs with Him.
But notice:
There are no promissory clauses for anyone, Jew or Gentile...
Who is not in Christ.