In the Letter to the Romans, we are told by the apostle Paul:
Romans 9:6: "But it is not as though the word of God has failed. For they are not all Israel who are descended from Israel..."
What does it mean to be "of Israel"?
Biblical Hermeneutics Stack Exchange is a question and answer site for professors, theologians, and those interested in exegetical analysis of biblical texts. It only takes a minute to sign up.Sign up to join this community
The answer to the question actually occurs later in the same passage of Rom 9:
6 It is not as though God’s word has failed. For not all who are descended from Israel are Israel. 7 Nor because they are Abraham’s descendants are they all his children. On the contrary, “Through Isaac your offspring will be reckoned.” 8 So it is not the children of the flesh who are God’s children, but it is the children of the promise who are regarded as offspring.
Note that the text makes a clear distinction between Abraham's biological children and the his spiritual children; between the biological children of Israel and the spiritual children of Israel.
The same idea is expressed in Gal 3 -
26 You are all sons of God through faith in Christ Jesus. 27 For all of you who were baptized into Christ have clothed yourselves with Christ. 28 There is neither Jew nor Greek, slave nor free, male nor female, for you are all one in Christ Jesus. 29 And if you belong to Christ, then you are Abraham’s seed and heirs according to the promise.
Thus, people "belonging to Christ" are the true spiritual heirs according to the promise. Paul says something similar is Rom 8:9 -
You, however, are controlled not by the flesh, but by the Spirit, if the Spirit of God lives in you. And if anyone does not have the Spirit of Christ, he does not belong to Christ.
Thus, we find that we have the following terms used equivalently:
Such people are to be clearly distinguished from those who