Ephesians 2:18-19

16 And [He designed] to reconcile to God both [Jew and Gentile, united] in a single body by means of His cross, thereby killing the mutual enmity and bringing the feud to an end.

17 And He came and preached the glad tidings of peace to you who were afar off and [peace] to those who were near.

18 For it is through Him that we both [whether far off or near] now have an introduction (access) by one [Holy] Spirit to the Father [so that we are able to approach Him].

19 Therefore you are no longer outsiders (exiles, migrants, and aliens, excluded from the rights of citizens), but you now share citizenship with the saints (God's own people, consecrated and set apart for Himself); and you belong to God's [own] household.

Plain and simple here, anyone who has been called and chosen by God is now a Jew, or a child of God, because we are now one with our Father through Christ. 

For he is not a [real] Jew who is only one outwardly and publicly, nor is [true] circumcision something external and physical. But he is a Jew who is one inwardly, and [true] circumcision is of the heart, a spiritual and not a literal [matter]. His praise is not from men but from God. Romans 2:28-29

This is why we need to beware of those who are constantly talking about our Father’s Covenant with Israel. Our Father made a covenant with Abraham and his offspring and Abraham’s offspring are those who are in Christ. Abraham’s offspring are born by faith authored and finished by Jesus, not those who are born from Israel. Just look at what Jesus constantly told the Israelites, He repeatedly told them that He was the only door, that He was the only way, and the only light. There are not two ways to get to our Father, there is one and the Old Covenant, the Covenant that was for Israel, has been done away with.  

However, it is not as though God's Word had failed [coming to nothing]. For it is not everybody who is a descendant of Jacob (Israel) who belongs to [the true] Israel. And they are not all the children of Abraham because they are by blood his descendants. No, [the promise was] Your descendants will be called and counted through the line of Isaac [though Abraham had an older son]. That is to say, it is not the children of the body [of Abraham] who are made God's children, but it is the offspring to whom the promise applies that shall be counted [as Abraham's true] descendants. Romans 9:6-8

In fact, their minds were grown hard and calloused [they had become dull and had lost the power of understanding]; for until this present day, when the Old Testament (the old covenant) is being read, that same veil still lies [on their hearts], not being lifted [to reveal] that in Christ it is made void and done away. 2 Corinthians 3:14

[My precaution was] because of false brethren who had been secretly smuggled in [to the Christian brotherhood]; they had slipped in to spy on our liberty and the freedom which we have in Christ Jesus, that they might again bring us into bondage [under the Law of Moses]. To them we did not yield submission even for a moment, that the truth of the Gospel might continue to be [preserved] for you [in its purity]. Galatians 2:4-5

The only way to find favor with our Father is by having Him freely bestow it upon you. Human lineage does not guarantee it, there is no work that can earn it, it is all grace. There are many who want to talk of a Covenant that our Father still has with Israel, when the Truth is the Old Covenant has been done away with. Jesus never speaks to the nation of Israel as if they will keep a special relationship with God apart from Him. Jesus actually speaks of them being destroyed without Him. So when you hear things like the Book of Revelation is only for the Israelites, or that the nation of Israel finds favor because of the Abrahamic Covenant, just go and read the Gospels and see what Jesus actually spoke. The Abrahamic Covenant has blessings for the children of faith, those who are truly Jews, those who are now one with Christ.  

Think of the history of Israel since Jesus. It has been one of destruction, pain, suffering, and blindness. It has been a history of war and death. The Covenant of Abraham in not for an earthly nation and it’s people, it is for the Kingdom of Heaven and its children. The nation of Israel enjoys no special favor over any other nation on this earth, our Father uses all nations. All power, all thrones, all dominions, whether seen or unseen, are under the control of our Father. In Christ we enjoy peace, joy, health, faith, hope, and love, we do not enjoy these things because of Israel.