In former generations this mystery was not made known to humankind, as it has now been revealed to his holy apostles and prophets by the Spirit: that is, the Gentiles have become fellow heirs, members of the same body, and sharers in the promise in Christ Jesus through the gospel. (Ephesians 3:5-6)
The adoption of believing Gentiles into the one people of God through the work of Christ is a central element of the Gospel. It’s almost as if the the inclusion of the Gentiles is the purpose of Christ’s life, death and resurrection. Paul argues this point explicitly in his letters. The gospels establish it through the use of narrative.
The Gospel of Luke is set exclusively in Judea and Galilee. The Acts of the Apostles, Luke’s second volume, is set throughout the Roman world. The Book of Acts witnesses the conversion of both Jews and non-Jews and the outpouring of the Holy Spirit on Jewish and Gentile believers. The small group of Jesus’ Jewish disciples grows into the world-wide church.
In Matthew’s gospel, Magi from the east come to pay homage to the newborn king. Matthew’s gospel concludes with Jesus’ command to make disciples of all nations. The intervening material relates primarily to Jesus’ ministry to the lost sheep of the house of Israel, but the birth and resurrection narratives set the gospel in its wider context.
Each author, in his own way, envisions Christ’s work as fulfilling the prophet’s vision. The nations of the world will find their blessing and live in peace with the people of Israel under the sovereignty of Israel’s God. God promised Abraham that through him all the people of the world would be blessed. As the gospel of Jesus Christ is preached among the nations, God’s promise to Abraham continues to come true.