Jeremiah prophesied a new covenant with Israel. The writings of the NT were to show that the Gentiles were included - and together would be one new man. All through the prophets, the Gentiles were prophesied to be included with Israel into the promise of the Messiah to come. It is in Him, that we are all part of the new covenant, as one.
Hebrews 8 and 9 explain it. The writer shows that the old covenant was ratified in the blood of animals. The New Covanent is ratified in the blood of Christ now. The blood saved Israel then, a shadow of what was to come int Christ. The blood of the New Covenant saves both Jew and Gentile.
1 Peter 1
17 And if ye call on the Father, who without respect of persons judgeth according to every man’s work, pass the time of your sojourning here in fear: 18 forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers; 19 but with the precious blood of Christ, as of a lamb without blemish and without spot: 20 who verily was foreordained before the foundation of the world, but was manifest in these last times for you, 21 who by him do believe in God, that raised him up from the dead, and gave him glory; that your faith and hope might be in God. 22 Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently: 23 being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth for ever. 24 For all flesh is as grass, and all the glory of man as the flower of grass. The grass withereth, and the flower thereof falleth away: 25 but the word of the Lord endureth for ever. And this is the word which by the gospel is preached unto you.
John 11
49 And one of them, named Caiaphas, being the high priest that same year, said unto them, Ye know nothing at all, 50 nor consider that it is expedient for us, that one man should die for the people, and that the whole nation perish not. 51 And this spake he not of himself: but being high priest that year,
he prophesied that Jesus should die for that nation; 52 And not for that nation only, but that also he should gather together in one the children of God that were scattered abroad.
Isa 49
Thus saith the Lord,
In an acceptable time have I heard thee,
and in a day of salvation have I helped thee:
and I will preserve thee,
and give thee for a covenant of the people,
to establish the earth,
to cause to inherit the desolate heritages;
9
that thou mayest say to the prisoners, Go forth;
to them that are in darkness, Shew yourselves.
They shall feed in the ways,
and their pastures shall be in all high places.
10
They shall not hunger nor thirst;
neither shall the heat nor sun smite them:
for he that hath mercy on them shall lead them,
even by the springs of water shall he guide them.
11
And I will make all my mountains a way,
and my highways shall be exalted.
12
Behold, these shall come from far:
and, lo, these from the north and from the west;
and these from the land of Sinim.
Isa 56
For thus saith the Lord unto the eunuchs that keep my sabbaths,
and choose the things that please me,
and take hold of my covenant;
5
even unto them will I give in mine house and within my walls
a place and a name better than of sons and of daughters:
I will give them an everlasting name, that shall not be cut off.
6
Also the sons of the stranger,
that join themselves to the Lord, to serve him,
and to love the name of the Lord, to be his servants,
every one that keepeth the sabbath from polluting it,
and taketh hold of my covenant;
7
even them will I bring to my holy mountain,
and make them joyful in my house of prayer:
their burnt offerings and their sacrifices shall be accepted upon mine altar;
for mine house shall be called an house of prayer for all people.
8
The Lord God which gathereth the outcasts of Israel saith,
Yet will I gather others to him,
beside those that are gathered unto him.
Is 59
For I the Lord love judgment,
I hate robbery for burnt offering;
and I will direct their work in truth,
and I will make an everlasting covenant with them.
9
And their seed shall be known among the Gentiles,
and their offspring among the people:
all that see them shall acknowledge them,
that they are the seed which the Lord hath blessed.
10
I will greatly rejoice in the Lord,
my soul shall be joyful in my God;
for he hath clothed me with the garments of salvation,
he hath covered me with the robe of righteousness,
as a bridegroom decketh himself with ornaments,
and as a bride adorneth herself with her jewels.
11
For as the earth bringeth forth her bud,
and as the garden causeth the things that are sown in it to spring forth;
so the Lord God will cause righteousness and praise
to spring forth before all the nations.
Mal 3
Behold, I will send my messenger, and he shall prepare the way before me: and the Lord, whom ye seek, shall suddenly come to his temple, even the messenger of the covenant, whom ye delight in: behold, he shall come, saith the Lord of hosts.
the language of God (Glick).
