The promise was passed down to Ephraim and Manassas which were the grand children of Israel. That promise never ended and is still in effect. Once the kingdom of Israel was split the 10 tribes were captured and eventual dispersed and many went north and to the west. So the real question is? Are you a part of Israel? and not are you Jewish.
Through faith in Jesus Christ, we are naturalized into the commonwealth of Israel and made one in Him. This spiritual unity transcends all earthly distinctions, making us members of the household of God and heirs to the promises made to the patriarchs.
When we receive the Holy Spirit, we are bound together in a common spiritual brotherhood. In the kingdom of God, social, racial, and gender distinctions do not create divisions. We are all one in Christ.
Gal 3:28-29
28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. 29 And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise.
The title "Israel" is a family name for overcomers. While many rely on physical descent, the Bible clarifies that the true Israel is composed of those who have the faith of Abraham.
Inward Reality vs. Outward Form:
Being a true Israelite is a matter of the heart and the Spirit, not merely physical lineage or outward ceremonies
Rom 2:28-29
28 For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: 29 But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God.
Rom 9:6-8
6 Not as though the word of God hath taken none effect. For they are not all Israel, which are of Israel: 7 Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called. 8 That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.
We are not isolated individuals but are built together into a holy priesthood to offer spiritual sacrifices.
"Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ." 1 Peter 2:5
In the final days, God's servants are identified as the "children of Israel" who receive His seal, representing a people without guile.
Rev 7:3-4
3 Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads. 4 And I heard the number of them which were sealed: and there were sealed an hundred and forty and four thousand of all the tribes of the children of Israel.
By abiding in the Vine, we receive the life-giving sap that makes us fruitful branches, united to the same Parent Stock, which is Christ. John 15:4-5