I ask instead, did Israel not understand? First, Moses says: “I will make you jealous by those who are not a nation; I will make you angry by a nation without understanding.”
19. But I say, has not Israel known? This objection of an opponent is taken from the comparison of the less with the greater. Paul had argued, that the Gentiles were not to be excluded from the knowledge of God, since he had from the beginning manifested himself to them, though only obscurely and through shadows, or had at least given them some knowledge of his truth.
The first words express the design of the apostle through these verses, that there is no difference between Jews and Gentiles, but they stand upon the same level in point of acceptance with God. In Jesus Christ there is neither Greek nor Jews, Col 3:11.
Commenting on Romans 10:12-21
But I say, did not Israel know? Some supply the word "God", did not Israel know God? verily, they did; they knew the being and perfections of God, the unity of God, and the trinity of persons in the divine essence; they knew the will of God, and the right way of worshipping him; for they were favoured with a divine revelation; to them were...