There are 36 occasions when 'Israel' is used in the NT; all are quoted below.
6 refer to Israel, the specific land, given to Abraham by God in an eternal, unconditional covenant. Gen 177,8
24 refer to the Jewish people of Israel.
5 refer to the God of Israel.
Not a single one refers to Gentile believers.
Geographical
But when Herod died, behold, an angel of the Lord appeared in a dream to Joseph in Egypt, saying, "Rise, take the child and his mother and go to the land of Israel, for those who sought the child's life are dead. And he rose and took the child and his mother and went to the land of Israel." Math 219-21
Centurian. When Jesus heard this, he marvelled and said to those who followed him, "Truly, I tell you, with no one in Israel have I found such faith." Math 810 Lu 79
Mute man healed. And the crowds marvelled, saying, "Never was anything like this seen in Israel." Math 933
Apostles sent out. When they persecute you in one town, flee to the next, for truly, I say to you, you will not have gone through all the towns of Israel before the Son of Man comes. Math 1023
At Calvary. He saved others; he cannot save himself. He is the King of Israel; let him come down now from the cross, and we will believe in him. Math 2742 Mk 1532
Jesus in Nazareth synagogue: I tell you, there were many widows in Israel in the days of Elijah ... And there were many lepers in Israel in the time of the prophet Elisha. Lu 425,27
Jewish People
To Canaanite woman. He answered, "I was sent only to the lost sheep of the house of Israel." Math 1524
Jesus said to them, "Truly, I say to you, in the new world, when the Son of Man will sit on his glorious throne, you who have followed me will also sit on twelve thrones, judging the twelve tribes of Israel. Math 1928
"Which commandment is the most important of all?" Jesus answered, "The most
important is, 'Hear, O Israel: The Lord our God, the Lord is one. Mk 1229
Jesus quoted from Deut 64
Angel speaking to Zechariah concerning his son to be, John Baptist.
And he will turn many of the children of Israel to the Lord their God. Lu 116
Part of Magnificat. He has helped his servant Israel, in remembrance of his mercy, as he spoke to our fathers, to Abraham and to his offspring forever. Lu 154,55
John Baptist. The child grew and became strong in spirit, and he was in the wilderness until the day of his public appearance to Israel. Lu 180
Jesus to Apostles: That you may eat and drink at my table in my kingdom and sit on thrones judging the twelve tribes of Israel. Lu 2230
Two going to Emmaus concerning Jesus: But we had hoped that he was the one to redeem Israel. Lu 2421
John Baptist concerning the Lamb of God: For this purpose I came baptizing with water, that he might be revealed to Israel. Jn 131
Jesus to Nicodemus: "Are you the teacher of Israel and yet you do not understand these things?" Jn 310
Apostles ask Jesus: "Lord, will you at this time restore the kingdom to Israel?" Act 16
Peter at Pentecost: "Men of Israel, hear these words: ... Let all the house of Israel therefore know for certain that God has made him both Lord and Christ, this Jesus whom you crucified." Act 222,36
Peter after healing lame man. "Men of Israel, why do you wonder at this, or why do you stare at us, as though by our own power or piety we have made him walk?" Act 312
Peter before Jewish Council: "Let it be known to all of you and to all the people of Israel that by the name of Jesus Christ of Nazareth ..." Act 410
Not all Jews are saved. For not all who are descended from Israel belong to Israel, and not all are children of Abraham because they are his offspring. ...
And Isaiah cries out concerning Israel: "Though the number of the sons of Israel
be as the sand of the sea, only a remnant of them will be saved ...
But I ask, did Israel not understand? ...
But of Israel he says, "All day long I have held out my hands to a disobedient and
contrary people." Ro 96,7,27, 1019, 21
Paul testifies that he proves God has not rejected his people.
I ask, then, has God rejected his people? By no means! For I myself am an Israelite, a descendant of Abraham, a member of the tribe of Benjamin. God has not rejected his people whom he foreknew. Ro 111,2
Israel failed to obtain what it was seeking. Ro 117
'Replacement' theologians do not claim this verse for the Church!!
A partial hardening has come upon Israel, until the fullness of the Gentiles has come in. And in this way all Israel will be saved. Ro 1125,26
Remember that you were at that time separated from Christ, alienated from the commonwealth of Israel and strangers to the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ. Eph 212,13
If anyone else thinks he has reason for confidence in the flesh, I have more: circumcised on the eighth day, of the people of Israel, of the tribe of Benjamin ... Phil 34,5
Behold, the days are coming, declares the Lord, when I will establish a new covenant with the house of Israel and with the house of Judah ... For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my laws into their minds, and write them on their hearts, and I will be their God, and they shall be my people. Heb 89,10
You have some there who hold the teaching of Balaam, who taught Balak to put a stumbling block before the sons of Israel. Rev 214
And I heard the number of the sealed, 144,000, sealed from every tribe of the sons of Israel ... Rev 74
And on the gates the names of the twelve tribes of the sons of Israel were inscribed. Rev 2112
God of Israel
So that the crowd wondered, when they saw the mute speaking, the crippled healthy, the lame walking, and the blind seeing. And they glorified the God of Israel. Math 1531
Zechariah's prophecy. Blessed be the Lord God of Israel, for he has visited and redeemed his people. Lu 168
Simeon declared: My eyes have seen your salvation that you have prepared in the presence of all peoples, a light for revelation to the Gentiles, and for glory to your people Israel. ... "Behold, this child is appointed for the fall and rising of many in Israel." Lu 230-32, 34
Jesus saw Nathanael coming toward him and said of him, "Behold, an Israelite indeed, in whom there is no deceit!" ... Nathanael answered him, "Rabbi, you are the Son of God! You are the King of Israel!" Jn 147,49
At Triumphal entry. "Hosanna! Blessed is he who comes in the name of the Lord, even the King of Israel!" Jn 1213
Also
For neither circumcision counts for anything, nor uncircumcision, but a new creation. And as for all who walk by this rule, peace and mercy be upon them, and upon the Israel of God. Gal 615,16
[This blessing 'peace and mercy be upon them' is given first to Gentile believers,
that is upon 'all who walk by this rule'
AND the same blessing is given to Jewish believers, that is 'upon the Israel of God']