That is correct. Just look at Romans 9:6-8, Ephesians 2:11-22 and Galatians 6:15-16 to see the criteria for being a spiritual Israelite. It's equated to being a child of God and of the promise which all Christians are.
I don't understand your question. The two have already become one new man according to scripture and it happened by way of the shed blood of Christ. How can any Christian not understand this elementary concept?
Ephesians 2:11 Therefore, remember that formerly you who are Gentiles by birth and called “uncircumcised” by those who call themselves “the circumcision” (which is done in the body by human hands)— 12 remember that at that time you were separate from Christ, excluded from citizenship in Israel and foreigners to the covenants of the promise, without hope and without God in the world. 13 But now in Christ Jesus you who once were far away have been brought near by the blood of Christ. 14 For he himself is our peace, who has made the two groups one and has destroyed the barrier, the dividing wall of hostility, 15 by setting aside in his flesh the law with its commands and regulations. His purpose was to create in himself one new humanity out of the two, thus making peace, 16 and in one body to reconcile both of them to God through the cross, by which he put to death their hostility. 17 He came and preached peace to you who were far away and peace to those who were near. 18 For through him we both have access to the Father by one Spirit. 19 Consequently, you are no longer foreigners and strangers, but fellow citizens with God’s people and also members of his household, 20 built on the foundation of the apostles and prophets, with Christ Jesus himself as the chief cornerstone. 21 In him the whole building is joined together and rises to become a holy temple in the Lord. 22 And in him you too are being built together to become a dwelling in which God lives by his Spirit.
How much more clear can this be that the two (Jew and Gentile believers) have already become one new man? It says Jesus "has made the two groups one" and that we are now "fellow citizens" in the church with Jesus as the chief cornerstone.
You are mistaken. Read Ephesians 2:11-22 which explicitly teaches that the two have already been made one. How can you not understand this? The New Testament repeatedly teaches how there is "neither Jew nor Gentile" in the church and there is no difference between them in the church and that we are all one in Christ Jesus. You need to ask God for wisdom and start reading the New Testament.
That is absolutely false. That contradicts a ton of New Testament scripture, including Ephesians 2:11-22.
Acts 15:7 And when there had been much disputing, Peter rose up, and said unto them, Men and brethren, ye know how that a good while ago God made choice among us, that the Gentiles by my mouth should hear the word of the gospel, and believe. 8 And God, which knoweth the hearts, bare them witness, giving them the Holy Ghost, even as he did unto us; 9 And put no difference between us and them, purifying their hearts by faith.
Romans 10:12 For there is no difference between Jew and Gentile—the same Lord is Lord of all and richly blesses all who call on him, 13 for, “Everyone who calls on the name of the Lord will be saved.”
Galatians 3:26 So in Christ Jesus you are all children of God through faith, 27 for all of you who were baptized into Christ have clothed yourselves with Christ. 28 There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus. 29 If you belong to Christ, then you are Abraham’s seed, and heirs according to the promise.
1 Corinthians 12:Just as a body, though one, has many parts, but all its many parts form one body, so it is with Christ. 13 For we were all baptized by one Spirit so as to form one body—whether Jews or Gentiles, slave or free—and we were all given the one Spirit to drink.
Colossians 3:11 Here there is no Gentile or Jew, circumcised or uncircumcised, barbarian, Scythian, slave or free, but Christ is all, and is in all. 12 Therefore, as God’s chosen people, holy and dearly loved, clothe yourselves with compassion, kindness, humility, gentleness and patience.
