When we receive the Holy Spirit we are adopted in the family of God, we become heirs, Gentile and Jews alike.
Galatians 4:6-7
6) And because yue are sons, God hath sent forth the Spirit of His Son into your hearts, crying, Abba, Father.
7) Wherefore thou aret no more a servant, but a son; and if a son, then a heir of God through Christ. see also Romans 8:14-18
Ephesians 2:12-22
12) That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world,
13) But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
14) For He is our peace, who hath made both one, and hath broken down the middle wall of parition between us.
15) Having abolished in His flesh the enmity, even the law of commandments contained in the ordinanaces; for to make in Himself of twain one new man, so making peace.
16) And that He might reconcile both unto God in one body by the cross, having slain the enmity thereby:
17) And came and preached peace to you which were afar off, and to them that were nigh.
18) For though HIm we both have access by one Spirit unto the Father.
19) Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God;
20) And are built upon the foundation of the apostles and prophets, Jesus Christ Himself being the chief corner stone;
21) In whom all the building fitly framed together groweth unto an holy temple in the Lord:
22) In whom ye also are builded together for an habitation of God through the Spirit.
So yes, in Christ we are one, for it is a high priviledge to be born Jewish, but even so much better to be born again (John 3:3; 7), for we are made heir of Christ--Abraham's seed. (Galatians 3:27-29)