An unpopular but biblically sound doctrine is the Israel of God.
This is not Anglo-Israeli-ism.
This is not replacement theology.
This is Spirit Israel.
No less than the scholarly Paul the Apostle draws down the distinction between the physical Jew and the spiritual Jew:
Romans 9:1-6 (KJV)
1 I say the truth in Christ, I lie not, my conscience also bearing me witness in the Holy Ghost,
2 That I have great heaviness and continual sorrow in my heart.
3 For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh:
4 Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises;
5 Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen.
6 Not as though the word of God hath taken none effect.
For they are not all Israel, which are of Israel:
and:
Romans 2:28-29 (KJV)
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.
"praise" in verse 29 is the literal definition of "Jew" from Judah (Genesis 29:35). whose jewishness is not of men but of God.
The circumcision of the heart (which includes females btw) is at least as old as:
Deuteronomy 10:16 (KJV)
16 Circumcise therefore the foreskin of your heart, and be no more stiffnecked.
So the distinction between the physical and the spiritual goes at least as far back as this (and IMHO, all the way back to Eden).
Recall also that in Christ...
Galatians 3:24-28 (KJV)
24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.
25 But after that faith is come, we are no longer under a schoolmaster.
26 For ye are all the children of God by faith in Christ Jesus.
27 For as many of you as have been baptized into Christ have put on Christ.
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.