Ephesians 2:19 (ESV) … “So then you are no longer strangers and aliens, but you are fellow citizens with the saints and members of the household of God…”
Redeemed Jews and Gentiles are no longer estranged from each other but are fellow citizens of the kingdom of God. Race or nationality make no difference. All are redeemed people through Christ’s cross. God’s people represents the niv interpretation of the Greek hagion, literally, “holy ones.”
Other interpreters see the holy ones as Israel, Jewish Christians, the first Christian generation, all believers, or the angels of heaven. The contrast may be between who the Gentiles were—aliens—and who they now are—kingdom citizens along with those who have always been kingdom citizens—Jews. In that case they have extended the meaning of holy ones so that it is no longer limited to Jews but also includes Gentiles, now meaning all believers.
The reference could maintain the discussion of being seated in the heavenly realm and allude to the angels as other inhabitants there. Most likely, it is a general reference to people of God from all generations and uses the contrast of the Gentiles’ previous state to enhance the understanding of their present state. Alienated foreigners with no citizenship papers, they have joined the people of God with heavenly citizenship. Not only are they citizens of a heavenly kingdom, but they are also members of a spiritual family, God’s household.
Sin has divided mankind, but Christ unites by His Spirit. All believers, regardless of national background, belong to that “holy nation” with citizenship in heaven.