Romans 11:30-31

“ For as ye also in time past disobeyed God, but have now obtained mercy by their disobedience; even so have these also now been disobedient, that by the mercy shown to you they also may obtain mercy. ”

The entire course of the religious history of the world is determined by the antagonism created among mankind by the calling of Abraham, between a people specially destined by God to receive His revelations, and the other nations given over to themselves. From that moment (Genesis 12) there begin to be described those two immense curves which traverse the ages of antiquity in opposite directions, and which, crossing one another at the advent of Christianity, are prolonged from that period in inverse directions, and shall terminate by uniting and losing themselves in one another at the goal of history.

Ver. 30 describes the rebellion of the Gentiles, then their salvation determined by the rebellion of the Jews; and Romans 11:31, the rebellion of the Jews, then their salvation arising from the salvation of the Gentiles.