Albert Barnes Commentary Romans 11:19

"Thou wilt say then, Branches were broken off, that I might be grafted in." — Romans 11:19 (ASV)

You will say then. You who are a Gentile.

The branches were broken off, etc. The Jews were rejected in order that the gospel might be preached to the Gentiles. This would seem to follow from what the apostle had said in Romans 11:11-12. Perhaps it might be said that there was some reason for exultation from the fact that God had rejected his ancient people to make a way open to admit the Gentiles to the church. The objection is, that the branches were broken off in order that others might be grafted in. To this Paul replies in the next verse, that this was not the reason why they were rejected, but their unbelief was the cause.