Gentile Christians take an inordinate pride is trying to connect themselves to being spiritual Israel or a spiritual Jew. But that can't be because to be a Jew or a spiritual Jew one would have to be from the tribe of Judah from which that designation originates.
They also try to link themselves as being a son of Abraham using this passage of Scripture in Paul's letter to Jewish Christians in the Galatian area:
29 And if ye be Christ’s, then are ye Abraham’s seed, and heirs according to the promise. Gal. 3:29.
But Paul is writing to Jewish Christians who were unsure of their Messiah's arrival and His effect upon the Abrahamic and Mosaic Covenants:
23 But before faith came, we [Jews] were kept under the law, shut up unto the faith which should afterwards be revealed.
24 Wherefore the law was our schoolmaster to bring us [Jews] unto Christ, that we [Jews] might be justified by faith.
25 But after that faith is come, we [Jews] are no longer under a schoolmaster [the Law].
26 For ye [Jews] are all the children of God by faith in Christ Jesus [Your Messiah].
27 For as many of you [Jews] 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 [Jews] one in Christ Jesus.
29 And if ye [Jews] be Christ’s, then are ye Abraham’s seed, and heirs according to the promise. Gal. 3:23–29.
No change. If you are Abraham's descendant seed, then you are also Christ's and heirs according to the Abrahamic Covenant Promises for God made no promises to Gentiles in the Abrahamic Covenant nor in the New Covenant Promise of Jeremiah 31.
Not even Abraham was a Jew. He was Hebrew from the line of Eber a descendant through Shem. Stay with me now.
Recently there was discussion about the "synagogue" of Satan in Revelation 2:9. Here is the Scripture:
8 And unto the angel of the church in Smyrna write; These things saith the first and the last, which was dead, and is alive;
9 I know thy works, and tribulation, and poverty, (but thou art rich) and I know the blasphemy of them which say they are Jews, and are not, but are the synagogue of Satan. Rev. 2:8–9.
The Greek word translated "synagogue" in 2:9 means an "assemblage [of persons.]" It doesn't refer to Jews but is a word that merely means an "assemblage [of persons.]" It can mean an "assemblage" of Gentile Christians on Sunday morning or an "assemblage" of persons at a football game. There is nothing linking "synagogue" to Jews.
So, when is a Jew not a Jew? Jesus gives the answer in Rev. 2:9.
9 I know thy works, and tribulation, and poverty, (but thou art rich) and I know the blasphemy of them which say they are Jews, and are not, but are the synagogue of Satan. Rev. 2:9.
Jesus would know who a true Jew is and who isn't, and in this passage, there is a confession to Jewry but Jesus who knows the 'hearts' of all says they are not Jews. There is no birthright to Judah or back to Abraham to those who say they are a descendant or son of Abraham. But Paul writing to Jewish Christians says that if you are Christ's, you are a descendant of Abraham according to the Promise God made to Abraham. So, what is this "assemblage" [of persons] that claim to be Jews and are not Jews? Maybe it's the false belief that Paul is writing to Gentile Christians - which he isn't - that because you belong to Jesus Christ that you are a descendant of Abraham. But that can't be for Gentiles do not come from the loins of Abraham nor is there any passage of Scripture in the First Covenant of God ever making covenant with Gentiles. None. Paul makes this clear in writing to Jewish Christians at Rome:
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. Rom. 9:4–5.
Everything regarding the above upon which salvation rests belong to Israel. Paul says so. There's no mention of Gentiles possessing any of the above. Even Christ's arrival was fulfilled prophecy and covenant, and Christ's very words state He was sent to the lost sheep of the House of Israel, not the house of Gentiles. So, when is a Jew not a Jew?
When they claim to be of Abraham or Judah and there is just no biblical passage of Scripture that says this. Only in the minds of Gentiles that believe Paul's letters were written to Gentiles and interpret his words as such.
So, this synagogue or assemblage who say they are of Abraham or Judah are not from Abraham or Judah. How can they be? Gentiles do not come from the loins of Abraham or the tribe of Judah and Paul's words to the Jewish Christians in the Galatian region were addressed to the true sons of Abraham who did not know what the effect Israel's Messiah had on the Abrahamic Covenant, and the adoption, and the glory, and the giving of the Law, and the service of God, and the promises, whose are the fathers, and of whom as concerning the flesh Christ came.
John the Baptist agrees:
31 And I knew him not: but that he should be made manifest to Israel, therefore am I come baptizing with water. Jn. 1:31.
So, when is a Jew not a Jew? When they make claims to Abraham or the tribe of Judah that just does not exist.
Maybe THEY are of the assemblage of Satan?
Think it through, Gentile Christian.
Revelations was written to the Jewish Christians about things about to shortly take place. You don't want to be on the wrong side of history.
Or of Christ.