Ephesians 3:2-3, 5-6

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.

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. This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel.