Consider a few things that Paul said in Romans 10, then. He was writing in Greek, so it is not always clear when he meant the Divine Name.
If you confess with your lips, "Jesus is Lord" and believe in your heart that God raised him from the dead, you will be saved. (Romans 10:9)Shortly after, Paul continues:
For there is no difference between Jew and Gentile -- the same Lord is Lord of all and richly blesses all who call on him, for "everyone who calls on the name of the Lord will be saved." (Romans 10:12-13)Just from reading Paul, it's likely that he meant "Jesus" as the "Lord" he was referring to in both the passages quoted above. At the end of the second passage, Paul is quoting the prophet Joel. The writings of Joel are available in Hebrew, so we do know when Joel meant the Divine Name; Paul also would have known this. Based on the Hebrew, many Bibles render that passage of Joel in English like this:
Everyone who calls in the name of the LORD will be saved. (Joel 2:32)Did Paul mean to parallel that passage from Joel, when he said:
If you confess with your lips, "Jesus is Lord" and believe in your heart that God raised him from the dead, you will be saved. (Romans 10:9)As the saying goes, "Read the whole thing" about what Paul said. In context, there are additional reasons to believe Paul is referring to Jesus in "Everyone who calls on the name of the Lord will be saved." Consider Paul's next point:
How, then, can they call on the one they have not believed in? And how can they believe in the one of whom they have not heard? And how can they hear without someone preaching to them? And how can they preach unless they are sent? As it is written, "How beautiful on the mountain are the feet of him who brings good news." (Romans 10:14-15)
At the end of that passage, Paul is quoting the prophet Isaiah (52:7). Again, these words are available in the original Hebrew. I would like to point out two things about the passage Paul quotes from Isaiah. First: Paul is quoting a prophecy about announcing the return of the LORD to Jerusalem and how the whole world will see the salvation of God; that is appropriate to Paul's point about sending messengers out into the world so that all who call on the name of the Lord will be saved. Second: That Isaiah passage is the immediate prelude to the passage of the suffering servant. That, again, is in line with Paul's point.
Paul carries much of his presentation to the Romans with quotes from the Old Testament. In some places, he is providing commentary on those passages for his readers, a Bible study as he goes along. (I could almost see it as Paul's Commentary on Isaiah and Joel in places.) While my thoughts on this are still forming, I will say: it is interesting to see how Paul sees the Scriptures that he grew up with, after learning about Jesus.