Under the Old Testament ancient Israel consisted of those who were physical descendants of Abraham, as well those who were Gentiles who became Jews by conversion.
Allow me to give you one example from scripture: During the time of Esther, King Ahasuerus reigned over 127 provinces reaching from India to Ethiopia (Esther 1:1; 8:17) and many Gentiles in those provinces converted and BECAME JEWS.
There are also other examples in scripture of Gentiles who became Jews, and there are instructive scriptures in the Old Testament which address how the Jews were to accept those Gentiles who would be grafted into Israel from the outside.
Many Christians who hold to unwavering support of the modern state of Israel do so because they think the Jews in Israel are the direct descendants of Abraham and consequently are in covenant with God, yet they never consider the question: “What about the converted Jews?”
Did you know the modern state of Israel recognizes and grants citizenship to converted Jews? Many never think this one through.
If you believe that modern Israel in the Middle East is the fulfillment of Bible prophecy, allow me to ask a very simple question and give you something to consider: What about converted Jews?
Do you consider converted Jews (formerly Gentiles) to be real Jews and in covenant with God?
If not, why? They were in scripture and If you are going to claim that modern Israel is in covenant with God you must go all the way and accept converted Jews (formerly Gentiles) because converted Jews were in covenant with God (via Israel’s covenant) in the Old Testament.
If modern Israel is in covenant with God then converted Jews are as well, which would mean that Gentiles have a route into covenant with God WITHOUT Jesus Christ!
Such theology ought to alarm you, for there is no covenant relationship with God apart from Jesus Christ: not for the Jew or the Gentile.