Direct Answer
Based on the speaker’s use of Romans 9:3–11, belonging to God’s people is not guaranteed by ethnicity or external attachment, but by faithful allegiance to Jesus the King; this confronts ethnic pride and also casual assumptions that one “belongs” without obedience. Early Christians, as the speaker presents it, would have understood their identity as “the Church of God… the new Israel,” whose first loyalty is to Jesus rather than to the nations.