Moses said it himself: 5"The person who does the commandments shall live by them." That was never in dispute. The law was a path to life, in theory, if anyone could walk it without ever stumbling. Paul has spent a letter showing that no one can, so he turns to another voice, the righteousness that is by faith, and lets it speak in Moses' own words, borrowed from a different passage.
6"Do not say in your heart, 'Who will ascend into heaven?'" as though Christ still had to be fetched down from somewhere far off. And someone would have to descend into the abyss to retrieve him from the dead. Both questions assume that the object of faith is distant and locked away, and that it needs a heroic expedition to reach. Paul answers from the same passage: 8"The word is near you, in your mouth and in your heart." A word already on the tongue, waiting to be spoken.
The promise follows: confess with your mouth that Jesus is Lord, believe in your heart that God raised him, and you will be saved. The word for confess means, literally, to say the same thing, to agree aloud with what is already true. And the word Lord, which Paul returns to again and again, is the word the Greek Old Testament uses for the name of God himself. When Paul closes by quoting Joel, 13"everyone who calls on the name of the Lord will be saved," he quotes a verse originally spoken of the LORD, the covenant name of Israel's God, and applies it without hesitation to Jesus.
In a world where "Caesar is lord" was the standard civic confession, saying "Jesus is Lord" was a risk as well as a creed, and Paul's first readers were saying it in the shadow of the imperial city. The confession is public by nature. It places a person's ultimate loyalty under one name and takes it out from under every other. Paul adds a promise in verse 11: 11"Everyone who believes in him will not be put to shame." The person who says the name aloud in a hostile place is not left exposed.
10"With the heart one believes and is justified, and with the mouth one confesses and is saved." Both matter. A silent, private belief that never reaches the mouth falls short of what Paul describes, just as a confession without belief is empty noise. The two move together, heart and mouth, because the salvation Paul describes was never meant to stay hidden inside a person.
12"There is no distinction between Jew and Greek," for the same Lord is Lord of all, 12"bestowing his riches on all who call on him." The word is near in every sense, close enough for anyone to reach without a special qualification, needing only the confession already forming on the lips of anyone who believes.
Ask what you believe in your heart that you have not yet said aloud, and to whom.
Prayer
Father, thank you that you never asked us to climb to heaven or descend to the dead to find you. Thank you that the word of faith has always been as near as our own mouths and hearts. Let our lips confess what our hearts believe, that Jesus is Lord, raised from the dead, the Lord of all who call on his name. In Jesus' name, amen.