Romans 11:21

21.For if God has not spared the natural branches, etc. This is a most powerful reason to beat down all self-confidence: for the rejection of the Jews should never come across our minds without striking and shaking us with dread. For what ruined them, but that through supine dependence on the dignity which they had obtained, they despised what God had appointed? They were not spared, though they were natural branches; what then shall be done to us, who are the wild olive and aliens, if we become beyond measure arrogant? But this thought, as it leads us to distrust ourselves, so it tends to make us to cleave more firmly and steadfastly to the goodness of God.

And here again it appears more evident, that the discourse is addressed generally to the body of the Gentiles, for the excision, of which he speaks, could not apply to individuals, whose election is unchangeable, based on the eternal purpose of God. Paul therefore declares to the Gentiles, that if they exulted over the Jews, a reward for their pride would be prepared for them; for God will again reconcile to himself the first people whom he has divorced.