Romans 10:19-21 : But I say Did Israel not know? First Moses saith, I will provoke you to jealousy with that, which is no nation, With a nation void of understanding will I anger you. And Isaiah is very bold, and saith, I was found of them that sought me not; I became manifest unto them that asked not of me. But as to Israel he saith, All the day long did I spread out my hands unto a disobedient and gain-saying people. "Did Israel not know?" This refers to what is said in Romans 10:18 : "Yea, verily, their sound went out into all the earth, and their words unto the ends of the world." From this prophecy, quoted from Isaiah, Israel should have known that the gospel was to go "out into the earth," "unto the ends of the world" to the Gentiles as well as to the Jews. The Jews, therefore, should not have been angered, or even surprised, that the gospel was being preached to the Gentiles, as their own prophet had foretold. "But I say, Did Israel not know?" If they did not, it was because they were so blinded by their own conceits that they could not understand plain language. Even Moses had said: "I will provoke you to jealousy with that which is no nation, with a nation void of under-standing will I anger you." The Jews were so opposed to the Gentiles that they wanted no consideration given them.
Even many of the professed Christians of the Jews were enraged at Paul for his work among the Gentiles. "And Isaiah is very bold, and saith, I was found of them that sought me not; I became manifest unto them that asked not of me." It is true in a sense that men must seek after God, but they cannot do so unless they know something of him and the Gentiles were so lost in ignorance that they did not know to seek God until he was made known to them. Hence, it is literally true that God first sought the Gentiles.
They could not ask anything of Jehovah of whom they knew nothing. He had first to make himself manifest to them. This he did by sending his preachers out among them. But to Israel, who should have readily obeyed the gospel, God said: "All the day long did I spread out my hands unto a disobedient and gainsaying people." These Jews not only disobeyed, but spoke against God's message to them. As an illustration of this, see Acts 13:45; Acts 18:5-6.