“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” (v6). Paul was so overwhelmed by God’s grace that he called it a “mystery” four times (v3,4,6,9). The long-awaited Messiah, fulfiller of all God’s promises, came to save Jews and Gentiles both and make them “members of the same body.” Paul’s ancestors didn’t understand, but this truth “has now been revealed to his holy apostles and prophets by the Spirit” (v5).
In Jesus, impossible cultural barriers are broken down, and we become one family. God wants His surprising, wonderful, eternal plan to shine “through the church” to the world (v10).