Romans 10:1 Brethren, my heart's desire and my prayer to God for them is for their salvation. 2 For I testify about them that they have a zeal for God, but not in accordance with knowledge. 3 For not knowing about God's righteousness and seeking to establish their own, they did not subject themselves to the righteousness of God.
Paul loves the Jews, despite the fact they are lost. Paul confirms his statements in Romans 9 that the Jews seek salvation through the Law. Paul also claims that they are not hardened beyond salvation, just as he did in Romans 9:25.
4 For Christ is the end of the law for righteousness to everyone who believes. 5 For Moses writes that the man who practices the righteousness which is based on law shall live by that righteousness. 6 But the righteousness based on faith speaks as follows: "DO NOT SAY IN YOUR HEART, `WHO WILL ASCEND INTO HEAVEN?' (that is, to bring Christ down), 7 or `WHO WILL DESCEND INTO THE ABYSS?' (that is, to bring Christ up from the dead)." 8 But what does it say? "THE WORD IS NEAR YOU, IN YOUR MOUTH AND IN YOUR HEART"--that is, the word of faith which we are preaching, 9 that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved; 10 for with the heart a person believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation. 11 For the Scripture says, "WHOEVER BELIEVES IN HIM WILL NOT BE DISAPPOINTED."
Again, Paul confirms the Gospel message was God’s message all along. The Israelites are rejected because they seek salvation through the Law and not the free offer of the Gospel as God had originally established. Those that believe the Gospel are saved.
12 For there is no distinction between Jew and Greek; for the same Lord is Lord of all, abounding in riches for all who call on Him; 13 for "WHOEVER WILL CALL ON THE NAME OF THE LORD WILL BE SAVED."
Paul here affirms that salvation is for both Jews and Gentiles, based on faith in Christ. Salvation was never for the Jews alone or based on nationality. Rather, God had planned to save believers.
14 How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher? 15 How will they preach unless they are sent? Just as it is written, "HOW BEAUTIFUL ARE THE FEET OF THOSE WHO BRING GOOD NEWS OF GOOD THINGS!" 16 However, they did not all heed the good news; for Isaiah says, "LORD, WHO HAS BELIEVED OUR REPORT?" 17 So faith comes from hearing, and hearing by the word of Christ. 18 But I say, surely they have never heard, have they? Indeed they have; "THEIR VOICE HAS GONE OUT INTO ALL THE EARTH, AND THEIR WORDS TO THE ENDS OF THE WORLD ." 19 But I say, surely Israel did not know, did they? First Moses says, "I WILL MAKE YOU JEALOUS BY THAT WHICH IS NOT A NATION, BY A NATION WITHOUT UNDERSTANDING WILL I ANGER YOU." 20 And Isaiah is very bold and says, "I WAS FOUND BY THOSE WHO DID NOT SEEK ME, I BECAME MANIFEST TO THOSE WHO DID NOT ASK FOR ME." 21 But as for Israel He says, "ALL THE DAY LONG I HAVE STRETCHED OUT MY HANDS TO A DISOBEDIENT AND OBSTINATE PEOPLE."
The call of God must be heard throughout the world. God is willing to have mercy on both Jews and Gentiles so the Gospel must spread. Israel’s rejection is affirmed to be due to their own obstinate unbelief and rejection of the Gospel call.