That's false doctrine and is a lie.
Yes, once upon a time, Israel was chosen as God's people:
Deut 14:2: For thou art an holy people unto the LORD thy God, and the LORD hath chosen thee to be a peculiar people unto himself, above all the nations that are upon the earth.
Israel's relationship to God was conditioned upon their obedience. If they fell away, which they inevitably did, He was going to destroy them Himself:
1 Kings 9:6,7: But if ye shall at all turn from following me, ye or your children, and will not keep my commandments and my statutes which I have set before you, but go and serve other gods, and worship them: Then will I cut off Israel out of the land which I have given them; and this house, which I have hallowed for my name, will I cast out of my sight; and Israel shall be a proverb and a byword among all people:
Again:
Deut 4:25,26: When thou shalt beget children, and children's children, and ye shall have remained long in the land, and shall corrupt yourselves, and make a graven image, or the likeness of any thing, and shall do evil in the sight of the LORD thy God, to provoke him to anger: I call heaven and earth to witness against you this day, that ye shall soon utterly perish from off the land whereunto ye go over Jordan to possess it; ye shall not prolong your days upon it, but shall utterly be destroyed.
For example, at Kadesh Barnea after the multitude followed the faithless spies' negative report, God was going to destroy them.
Num 14:11,12: And the LORD said unto Moses, How long will this people provoke me? and how long will it be ere they believe me, for all the signs which I have shewed among them? I will smite them with the pestilence, and disinherit them, and will make of thee a greater nation and mightier than they.
Again, after Korah and company were destroyed,
Num 16:41-47: But on the morrow all the congregation of the children of Israel murmured against Moses and against Aaron, saying, Ye have killed the people of the LORD. And it came to pass, when the congregation was gathered against Moses and against Aaron, that they looked toward the tabernacle of the congregation: and, behold, the cloud covered it, and the glory of the LORD appeared. And Moses and Aaron came before the tabernacle of the congregation. And the LORD spake unto Moses, saying, Get you up from among this congregation (viz. the entire nation of Israel), that I may consume them as in a moment. And they fell upon their faces. And Moses said unto Aaron, Take a censer, and put fire therein from off the altar, and put on incense, and go quickly unto the congregation, and make an atonement for them: for there is wrath gone out from the LORD; the plague is begun. And Aaron took as Moses commanded, and ran into the midst of the congregation; and, behold, the plague was begun among the people: and he put on incense, and made an atonement for the people.
Warned by Joshua
Josh 23:11-13: Take good heed therefore unto yourselves, that ye love the LORD your God. Else if ye do in any wise go back, and cleave unto the remnant of these nations, even these that remain among you, and shall make marriages with them, and go in unto them, and they to you: Know for a certainty that the LORD your God will no more drive out any of these nations from before you; but they shall be snares and traps unto you, and scourges in your sides, and thorns in your eyes, until ye perish from off this good land which the LORD your God hath given you.
Josh 23:16: When ye have transgressed the covenant of the LORD your God, which he commanded you, and have gone and served other gods, and bowed yourselves to them; then shall the anger of the LORD be kindled against you, and ye shall perish quickly from off the good land which he hath given unto you.
1 Kings 14:15-16: For the LORD will strike Israel, as a reed is shaken in the water. He will uproot Israel from this good land which He gave to their fathers, and will scatter them beyond the River, because they have made their wooden images, provoking the LORD to anger. And He will give Israel up because of the sins of Jeroboam, who sinned and who made Israel sin."
Israel exists only as a nation and a political entity which is a staunch ally of the United States. But the only way anybody will be a child of God is through Jesus Christ.
John 14:6: Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
John the Baptist even stated this: 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. And now also the axe 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. I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire: Whose fan is in his hand, and he will throughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire. (Matt 3:9-12)
The entirety of the Old Law was fulfilled at the Cross of Christ. The Old Law was thereby abolished, as was any notion of Israel being anything special to God.
Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace (Eph 2:15)
The only Jews who will be saved at the end of time will be those who renounce religious error and are faithful Christians.
The ridiculous dispensational nonsense that circulates among "Christians" is derived from twisted interpretations of Revelation as something to be fulfilled in the future. Yet Revelation very plainly sets forth the events were contemporary to the readers.
Rev 1:1 The Revelation of Jesus Christ, which God gave unto him, to shew unto his servants things which must shortly come to pass; and he sent and signified it by his angel unto his servant John:
Again,
Rev. 1:3 Blessed is he that readeth, and they that hear the words of this prophecy, and keep those things which are written therein: for the time is at hand.
Rom 10:1-9: Brethren, my heart's desire and prayer to God for Israel is, that they might be saved. For I bear them record that they have a zeal of God, but not according to knowledge. For they being ignorant of God's righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God. For Christ is the end of the law for righteousness to every one that believeth. For Moses describeth the righteousness which is of the law, That the man which doeth those things shall live by them. But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:) Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.) But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach; That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.