Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God;
Note 15 at Eph 2:19: Gentiles were strangers and foreigners ("aliens") to God and His people (Eph 2:12). "Strangers" were neither friends nor acquaintances, but rather outsiders. "Foreigners" were aliens who were permitted to reside in a country but who lived without any rights of citizenship and could be expelled without appeal.
Because of Christ's reconciling work on the cross, Paul used three metaphors in describing both the Jews' and the Gentiles' new position before God: (1) fellow citizens with God's people (this verse [New International Version] and Php 3:20 [NIV]), (2) of the same household (this verse; Mt 12:48-50, 23:8-9; Lu 8:21; Ro 8:29; Heb 2:11-12; Ga 6:10; Eph 3:15; and Phm 16), and (3) part of God's building (Eph 2:20-22, 1Co 3:9, and 1Pe 2:5).
Those who are now united with Christ through the new birth (see note 2 at Joh 3:3) are inseparably a part of God.