Today the meaning of being Jewish is disputed — a faith? a nationality? — but in Israeli society the principle of matrilineal descent remains widely accepted.
The above quote is from an article in the NYTimes entitled "How Do You Prove You're A Jew".
Seems the question of whether one is a true Jew or not has been around for some time. Reminds me of Paul's Words in Romans 9 "It is not as though God's word had failed. For not all who are descended from Israel are Israel. Nor because they are his descendants are they all Abraham's children. On the contrary, "It is through Isaac that your offspring will be reckoned." In other words, it is not the natural children who are God's children, but it is the children of the promise who are regarded as Abraham's offspring."
The truth is that on a physical level, it will become more and more difficult to discern "Who is a true Jew?" and "Who is not?". However, on a spiritual level, the true children of Abraham are identified as those who possess the same faith of Abraham, who trusted not in his own ability to keep the law, but who trusted in the promise of God, who could raise the dead, and give life to those who in themselves were powerless and helpless (to bring about the things God had promised). We read in Romans 4 "Abraham believed God, and it was credited to him as righteousness" and again "Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham's offspring—not only to those who are of the law but also to those who are of the faith of Abraham. He is the father of us all."
While physical ethnicity is of some use, what matters most is whether one is a true child of Abraham, trusting not in one's physical lineage for salvation, but in the provision of God that leads to salvation, namely Jesus Christ himself, who HIMSELF is the fulfillment of the imagery and statement referred to by Abraham when he said "God himself will provide the lamb for the burnt offering..." (Gen 22) To be a true Israelite, or true child of God, one must look to Christ who is the fulfillment of the covenant made with Abraham. As is written "Consider Abraham: "He believed God, and it was credited to him as righteousness." Understand, then, that those who believe are children of Abraham. The Scripture foresaw that God would justify the Gentiles by faith, and announced the gospel in advance to Abraham: "All nations will be blessed through you." So those who have faith are blessed along with Abraham, the man of faith."
1What then shall we say that Abraham, our forefather, discovered in this matter? 2If, in fact, Abraham was justified by works, he had something to boast about—but not before God. 3What does the Scripture say? "Abraham believed God, and it was credited to him as righteousness."
4Now when a man works, his wages are not credited to him as a gift, but as an obligation. 5However, to the man who does not work but trusts God who justifies the wicked, his faith is credited as righteousness. 6David says the same thing when he speaks of the blessedness of the man to whom God credits righteousness apart from works:
7"Blessed are they
whose transgressions are forgiven,
whose sins are covered.
8Blessed is the man
whose sin the Lord will never count against him."
9Is this blessedness only for the circumcised, or also for the uncircumcised? We have been saying that Abraham's faith was credited to him as righteousness. 10Under what circumstances was it credited? Was it after he was circumcised, or before? It was not after, but before! 11And he received the sign of circumcision, a seal of the righteousness that he had by faith while he was still uncircumcised. So then, he is the father of all who believe but have not been circumcised, in order that righteousness might be credited to them. 12And he is also the father of the circumcised who not only are circumcised but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised.
13It was not through law that Abraham and his offspring received the promise that he would be heir of the world, but through the righteousness that comes by faith. 14For if those who live by law are heirs, faith has no value and the promise is worthless, 15because law brings wrath. And where there is no law there is no transgression.
16Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham's offspring—not only to those who are of the law but also to those who are of the faith of Abraham. He is the father of us all. 17As it is written: "I have made you a father of many nations."[c] He is our father in the sight of God, in whom he believed—the God who gives life to the dead and calls things that are not as though they were.
18Against all hope, Abraham in hope believed and so became the father of many nations, just as it had been said to him, "So shall your offspring be."[d] 19Without weakening in his faith, he faced the fact that his body was as good as dead—since he was about a hundred years old—and that Sarah's womb was also dead. 20Yet he did not waver through unbelief regarding the promise of God, but was strengthened in his faith and gave glory to God, 21being fully persuaded that God had power to do what he had promised. 22This is why "it was credited to him as righteousness." 23The words "it was credited to him" were written not for him alone, 24but also for us, to whom God will credit righteousness—for us who believe in him who raised Jesus our Lord from the dead. 25He was delivered over to death for our sins and was raised to life for our justification.
1I speak the truth in Christ—I am not lying, my conscience confirms it in the Holy Spirit— 2I have great sorrow and unceasing anguish in my heart. 3For I could wish that I myself were cursed and cut off from Christ for the sake of my brothers, those of my own race, 4the people of Israel. Theirs is the adoption as sons; theirs the divine glory, the covenants, the receiving of the law, the temple worship and the promises. 5Theirs are the patriarchs, and from them is traced the human ancestry of Christ, who is God over all, forever praised! Amen.
6It is not as though God's word had failed. For not all who are descended from Israel are Israel. 7Nor because they are his descendants are they all Abraham's children. On the contrary, "It is through Isaac that your offspring will be reckoned." 8In other words, it is not the natural children who are God's children, but it is the children of the promise who are regarded as Abraham's offspring. 9For this was how the promise was stated: "At the appointed time I will return, and Sarah will have a son."
10Not only that, but Rebekah's children had one and the same father, our father Isaac. 11Yet, before the twins were born or had done anything good or bad—in order that God's purpose in election might stand: 12not by works but by him who calls—she was told, "The older will serve the younger." 13Just as it is written: "Jacob I loved, but Esau I hated."
14What then shall we say? Is God unjust? Not at all! 15For he says to Moses,
"I will have mercy on whom I have mercy,
and I will have compassion on whom I have compassion." 16It does not, therefore, depend on man's desire or effort, but on God's mercy. 17For the Scripture says to Pharaoh: "I raised you up for this very purpose, that I might display my power in you and that my name might be proclaimed in all the earth." 18Therefore God has mercy on whom he wants to have mercy, and he hardens whom he wants to harden.
19One of you will say to me: "Then why does God still blame us? For who resists his will?" 20But who are you, O man, to talk back to God? "Shall what is formed say to him who formed it, 'Why did you make me like this?' " 21Does not the potter have the right to make out of the same lump of clay some pottery for noble purposes and some for common use?
22What if God, choosing to show his wrath and make his power known, bore with great patience the objects of his wrath—prepared for destruction? 23What if he did this to make the riches of his glory known to the objects of his mercy, whom he prepared in advance for glory— 24even us, whom he also called, not only from the Jews but also from the Gentiles? 25As he says in Hosea:
"I will call them 'my people' who are not my people;
and I will call her 'my loved one' who is not my loved one," 26and,
"It will happen that in the very place where it was said to them,
'You are not my people,'
they will be called 'sons of the living God.' "
27Isaiah cries out concerning Israel:
"Though the number of the Israelites be like the sand by the sea,
only the remnant will be saved.
28For the Lord will carry out
his sentence on earth with speed and finality."
29It is just as Isaiah said previously:
"Unless the Lord Almighty
had left us descendants,
we would have become like Sodom,
we would have been like Gomorrah."
30What then shall we say? That the Gentiles, who did not pursue righteousness, have obtained it, a righteousness that is by faith; 31but Israel, who pursued a law of righteousness, has not attained it. 32Why not? Because they pursued it not by faith but as if it were by works. They stumbled over the "stumbling stone." 33As it is written:
"See, I lay in Zion a stone that causes men to stumble
and a rock that makes them fall,
and the one who trusts in him will never be put to shame."