Abraham’s family has always been a household of “faith” in the eyes of God. Being Jewish (Israel) has never been about race only. Throughout the Old Testament and into the New, there have always been Jewish converts.
In Matthew 23:15, Jesus says the following to the scribes and Pharisees:
Woe to you, scribes and Pharisees, hypocrites! For you travel across sea and land to make a single proselyte, and when he becomes a proselyte, you make him twice as much a child of hell as yourselves.
On the day of Pentecost, proselytes were gathered among the many (Acts 2:11) who heard Peter preach the gospel, and those to whom Peter preached were called “ye men of Israel” (Acts 2:22). The Jewish proselytes were included as part of “all the house of Israel”. ~ Acts 2:36
Throughout the book of Acts we have accounts of Jews attempting to make converts of Gentiles, and Paul’s letter to the Galatians was written to counter the teachings and influence of the Judaizers who were attempting to proselytize the Gentiles in Galatia.
In scripture, Jewishness has never been about “race only”. If a Jew were a Jew by race only, Jews would have never sought to make converts.
Those who “became Jews” (Esther 8:17) from among the 127 Providences over which King Ahasuerus reigned (from India to Ethiopia) during the time of Esther, became Jewish by conversion.
In Scripture, being Jewish has always been a matter of faith, and not race only.
The premise on which Christian Zionism is founded is a faulty one to begin with as it rejects the key component of a true Israelite, which is his spirituality, or faith!
In the New Testament, Jesus did not think the religious Jews of his day, those were opposed him, had any special privilege with God. When they claimed that Abraham was their Father, Jesus said, “If you were Abraham’s children, then you would do what Abraham did. As it is, you are looking for a way to kill me, a man who has told you the truth that I heard from God. Abraham did not do such things. You are doing the works of your own father”. ~ John 8
They responded “We are not illegitimate children, the only Father we have is God himself.” To which Jesus replied, “If God were your Father, you would love me, for I have come here from God. I have not come on my own; God sent me. Why is my language not clear to you? Because you are unable to hear what I say. You belong to your father, the devil, and you want to carry out your father’s desires. He was a murderer from the beginning, not holding to the truth, for there is no truth in him. When he lies, he speaks his native language, for he is a liar and the father of lies”. ~ John 8
Notice that Jesus told these ungodly Jews who were actual physical descendants of Abraham, “You belong to your father, the devil.”
Jesus continues; “And because I tell you the truth, ye believe me not. Which of you convinceth me of sin? And if I say the truth, why do ye not believe me? He that is of God heareth God’s words: ye therefore hear them not, because ye are not of God “. ~ John 8:45-47
Abraham’s children are those who are of faith that lead to Christ and who practice righteousness, for God’s promise to Abraham was to make him the father of many nations!
The church has not replaced Israel, because true Israelites in the eyes of God have always been the church. The church of Jesus Christ began with the remnant of godly Jews, who through faith believed Jesus is the Messiah. It is into this body that Gentiles who believe in the Messiah have been baptized by conversion, and have become members of the Israel of God! ~ Galatians 6:16