Rom 10:13 For "Everyone who calls on the name of the LORD will be saved."
Paul was quoting from the old testament.
Joel_2:32 And everyone who calls on the name of the Lord will be saved; for on Mount Zion and in Jerusalem there will be deliverance, as the Lord has said, even among the survivors whom the Lord calls
Keep in mind here that he is referring to Christ. You cannot become a Christian unless you put Christ in the equation.
Rom 10:14 But how can they call on Him to save them unless they believe in Him? And how can they believe in Him if they have never heard about Him? And how can they hear about Him unless someone tells them? Rom 10:15 And how will anyone go and tell them without being sent? That is why the Scriptures say, "How beautiful are the feet of messengers who bring good news!"
Life Application New Testament Commentary:
All believers are sent to announce this Good News. The process of salvation begins with the one who tells another the Good News. Like Paul and the early Christians, who spread the message of Christ despite persecution and even death, we should be eager to share this Good News of salvation to all who will listen. In the verse quoted from Isa_52:7, the herald is bearing good news to Judah about the end of their exile in Babylon and their return to their own land. His feet were beautiful to them, for his good news was so welcome. The message was what he brought, but it was those worn and dusty feet that brought him. Those feet were beautiful because they represented the messenger’s willingness to be sent with good news. Only now the message was not just for Israel, but for the whole world.
I would remind everyone that in Mathew 28:19 Therefore, go and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit. We are commanded to spread the good news in any way we can.
Rom 10:16 But not everyone welcomes the Good News, for Isaiah the prophet said, "LORD, who has believed our message?" Rom 10:17 So faith comes from hearing, that is, hearing the Good News about Christ. Rom 10:18 But I ask, have the people of Israel actually heard the message? Yes, they have: "The message has gone throughout the earth, and the words to all the world."
Rom 1:18 But God shows His anger from heaven against all sinful, wicked people who suppress the truth by their wickedness. Rom 1:19 They know the truth about God because He has made it obvious to them. Rom 1:20 For ever since the world was created, people have seen the earth and sky. Through everything God made, they can clearly see His invisible qualities—His eternal power and divine nature. So they have no excuse for not knowing God.
I think Paul was relatively clear on this point.
Rom 10:19 But I ask, did the people of Israel really understand? Yes, they did, for even in the time of Moses, God said, "I will rouse your jealousy through people who are not even a nation. I will provoke your anger through the foolish Gentiles." Rom 10:20 And later Isaiah spoke boldly for God, saying, "I was found by people who were not looking for Me. I showed Myself to those who were not asking for Me." Rom 10:21 But regarding Israel, God said, "All day long I opened My arms to them, but they were disobedient and rebellious."
Deuteronomy 32:21New International Version (NIV)
21 They made me jealous by what is no god and angered me with their worthless idols. I will make them envious by those who are not a people; I will make them angry by a nation that has no understanding.
Isaiah 65:1New International Version (NIV)
65 “I revealed myself to those who did not ask for me; I was found by those who did not seek me. To a nation that did not call on my name, I said, ‘Here am I, here am I.’
Isaiah 65:2New International Version (NIV)
2 All day long I have held out my hands to an obstinate people, who walk in ways not good, pursuing their own imaginations—
I think God has made it clear in his scriptures that the Jews had every opportunity at that time to hear the Gospel. The Last verse Isaiah 65:2 shows frustration with the Jews. The end times the Jews will again understand Jesus and become the 144,000. Hopefully you and I will be gone by then.