When Jesus came in the flesh, He caused division within Israel because He was the truth. As some believed in Him and others didn't, the Jews began to separate:

(John 7:43-44 KJV) So there was a division among the people because of him. {44} And some of them would have taken him; but no man laid hands on him.

(John 9:16 KJV) Therefore said some of the Pharisees, This man is not of God, because he keepeth not the sabbath day. Others said, How can a man that is a sinner do such miracles? And there was a division among them.

(John 10:19-21 KJV) There was a division therefore again among the Jews for these sayings. {20} And many of them said, He hath a devil, and is mad; why hear ye him? {21} Others said, These are not the words of him that hath a devil. Can a devil open the eyes of the blind?

Jesus Himself said:

(Luke 12:51-53 KJV) Suppose ye that I am come to give peace on earth? I tell you, Nay; but rather division: {52} For from henceforth there shall be five in one house divided, three against two, and two against three. {53} The father shall be divided against the son, and the son against the father; the mother against the daughter, and the daughter against the mother; the mother in law against her daughter in law, and the daughter in law against her mother in law.

THE DISCIPLES, NOT ISRAEL'S ELITE,
WITNESSED THE ANNOUNCING OF THE NEW COVENANT

Part of this division can be seen in the announcement of the New Covenant Jeremiah prophesied. Christ announced it to the Jewish disciples because they believed in Him. There were no officials of Israel, nor any of those in service to the temple, at the Passover meal with His disciples. He would certainly die and shed His blood for all in Israel, no matter what their office or state. They would also be given the opportunity to enter into the New Covenant at Pentecost by faith through the disciple's preaching, but not all did. Thus, the Jews were divided into two groups when Jesus came and walked among them as one of their own. And with the preaching of the gospel starting at Pentecost, this division became even more evident: those who believed proved themselves to be the spiritual sons of Abraham because of their faith in Christ. They were now adopted as sons of God. The writer to the Hebrews described the Church as having come to heavenly Jerusalem by faith through the blood of Christ:

(Heb 12:22-24 KJV) But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, {23} To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect, {24} And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel.

This was the Church of the firstborn, meaning Christ as being raised from the dead and giving the Holy Spirit to all who believed. Those who stayed under the Old Covenant in earthly Jerusalem by not believing, repenting and receiving the Holy Spirit remained the natural sons of Abraham.

When John the Baptist came preaching repentance to Israel, apparently the unbelieving Jews protested that they were children of Abraham, but John rebuked them, saying,

(Mat 3:8-10 KJV) Bring forth therefore fruits meet for repentance: {9} And think not to say within yourselves, We have Abraham to our father: for I say unto you, that God is able of these stones to raise up children unto Abraham. {10} And now also the ax is laid unto the root of the trees: therefore every tree which bringeth not forth good fruit is hewn down, and cast into the fire.

They said the same to Jesus, and His response was even stronger:

(John 8:37-40 KJV) I know that ye are Abraham's seed; but ye seek to kill me, because my word hath no place in you. {38} I speak that which I have seen with my Father: and ye do that which ye have seen with your father. {39} They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham's children, ye would do the works of Abraham. {40} But now ye seek to kill me, a man that hath told you the truth, which I have heard of God: this did not Abraham.

In these four verses, Jesus refers to the Jews of His time in two ways: those of natural Israel ("I know that you are Abraham's [physical] seed"), and then the spiritual seed of Abraham: ("If ye were Abraham's [spiritual] children, ye would do the works of Abraham"). The "works" Jesus refers to, of course, were those that come from one having the faith of Abraham. (See also John 15 and Romans 11.)

JESUS TOOK THE KINGDOM FROM THE UNBELIEVING RULERS
AND GAVE IT TO THE DISCIPLES

Jesus taught that the Kingdom promised to Israel was being taken from the unbelieving Jews [natural sons of Abraham] and given to the Jewish [spiritual] sons of Abraham who believed in Him and followed Him. Since the rulers of the Jews rejected our Lord, the promise of Messiah's Kingdom was taken from them. The promise of the Kingdom was NOT taken from Israel, but only from those Jews who rejected Christ:

(Mat 21:33-44 KJV) Hear another parable: There was a certain householder, which planted a vineyard, and hedged it round about, and digged a winepress in it, and built a tower, and let it out to husbandmen, and went into a far country: {34} And when the time of the fruit drew near, he sent his servants to the husbandmen, that they might receive the fruits of it. {35} And the husbandmen took his servants, and beat one, and killed another, and stoned another. {36} Again, he sent other servants more than the first: and they did unto them likewise. {37} But last of all he sent unto them his son, saying, They will reverence my son. {38} But when the husbandmen saw the son, they said among themselves, This is the heir; come, let us kill him, and let us seize on his inheritance. {39} And they caught him, and cast him out of the vineyard, and slew him. {40} When the lord therefore of the vineyard cometh, what will he do unto those husbandmen? {41} They say unto him, He will miserably destroy those wicked men, and will let out his vineyard unto other husbandmen, which shall render him the fruits in their seasons. {42} Jesus saith unto them, Did ye never read in the scriptures, The stone which the builders rejected, the same is become the head of the corner: this is the Lord's doing, and it is marvellous in our eyes? {43} Therefore say I unto you, The kingdom of God shall be taken from you, and given to a nation bringing forth the fruits thereof. {44} And whosoever shall fall on this stone shall be broken: but on whomsoever it shall fall, it will grind him to powder.

The leaders of Israel rejected Jesus, but to those who believed on Him, He became the cornerstone of the remnant who would carry His gospel to the world. The reaction of those who rejected Him was the usual one of anger and a desire to get rid of Him:

(Mat 21:45-46 KJV) And when the chief priests and Pharisees had heard his parables, they perceived that he spake of them. {46} But when they sought to lay hands on him, they feared the multitude, because they took him for a prophet.

Those who did not reject Him became the Church built on Himself as its Rock:

(Mat 16:15-21 KJV) He saith unto them, But whom say ye that I am? {16} And Simon Peter answered and said, Thou art the Christ, the Son of the living God. {17} And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. {18} And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. {19} And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven. {20} Then charged he his disciples that they should tell no man that he was Jesus the Christ. {21} From that time forth began Jesus to show unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day.

The Jewish disciples were promised the positions of authority in Messiah's Kingdom in the place of the Jewish leaders who rejected Him:

(Luke 12:32 KJV) Fear not, little flock; for it is your Father's good pleasure to give you the kingdom.

(Luke 22:28-30 KJV) Ye are they which have continued with me in my temptations. {29} And I appoint unto you a kingdom, as my Father hath appointed unto me; {30} That ye may eat and drink at my table in my kingdom, and sit on thrones judging the twelve tribes of Israel.

Not all Israel rejected Jesus Christ. The disciples and many other Jews were elect of God to believe. The rest were blinded. God fulfilled His "New Covenant with the house of Israel" in the Jews who accepted Jesus as the Messiah, and they went forth with the gospel to entreat more to come to Him through His finished work. All of these Scriptural facts caused Paul to ask some pertinent questions followed by some pertinent answers:

(Rom 11:1-7 KJV) I say then, Hath God cast away his people? God forbid. For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin. {2} God hath not cast away his people which he foreknew. Wot ye not what the scripture saith of Elias? how he maketh intercession to God against Israel, saying, {3} Lord, they have killed thy prophets, and digged down thine altars; and I am left alone, and they seek my life. {4} But what saith the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal. {5} Even so then at this present time also there is a remnant according to the election of grace. {6} And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then is it no more grace: otherwise work is no more work. {7} What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.

Here Paul protests against the idea that God was totally done with Israel. He says he himself is a Jew under the New Covenant, so that could not be true. But the ax had definitely been laid to the tree. The unbelieving part of Israel was cut off, and a foreknown, believing Jewish remnant formed the Church who would preserve and proclaim the finished work of Christ until the time when God again grafts natural Israel back into the olive tree, according to His plan.