The reading is from St. Paul's Letter to the Ephesians 2:19-22; 3:1-7

Brethren, you are no longer strangers and sojourners, but you are fellow citizens with the saints and members of the household of God, built upon the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone, in whom the whole structure is joined together and grows into a holy temple in the Lord in whom you also are built into it for a dwelling place of God in the Spirit. For this reason I, Paul, a prisoner for Christ Jesus on behalf of you Gentiles -- assuming that you have heard of the stewardship of God's grace that was given to me for you, how the mystery was made known to me by revelation, as I have written briefly. When you read this you can perceive my insight into the mystery of Christ, which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit; that is, how the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel. Of this gospel I was made a minister according to the gift of God's grace which was given me by the working of his power.