John Chrysostom

"It groweth," saith he, "into a holy temple in the Lord, in whom ye also," he adds, "are builded together." He is speaking continuously: "Into a holy temple, for a habitation of God in the Spirit." What then is the object of this building? It is that God may dwell in this temple. For each of you severally is a temple, and all of you together are a temple. And He dwelleth in you as in the body of Christ, and as in a Spiritual temple. …

Homily on Ephesians 6 ↗

Theophylact of Ohrid

And all believers are built up in Him, and you also, Ephesians, to be a dwelling place of God in the Spirit, that is, through the cooperation of the Spirit. Or else he said "in the Spirit" in contrast to a material building, as if saying: a spiritual dwelling place of God. Such building up is also accomplished until the second coming through believers.

Commentary on Ephesians ↗

Thomas Aquinas

Finally, he indicates how the Gentiles have become participants of the building. "In which" building not only are the Jews incorporated, but also you Ephesians "are built together," that is, you are incorporated like the others. "Come to him, the living stone, rejected indeed by men, but chosen and honored by God. Be yourselves like living stones built into a spiritual house" (1 Pet 2:4-5). Therefore he adds "into an habitation of God" that God may dwell in you through faith. …

Commentary on Ephesians ↗