As we read Romans we need to keep in mind that Paul’s primary audience were Jewish believers in Christ in Rome. They had a deep foundation in the old testament, especially in the Torah, so when Paul brings a few words from Deuteronomy, we read the few words, but they would have immediately known the full story, characters and messages.
Moses is giving the people a choice that they will have to make just before handing the leadership role over to Joshua to take them into the promised land. He paints it very clearly: I set before you today life and prosperity, death and destruction. You get to choose. Love God and follow His commandments or turn your hearts away, become disobedient and worship other gods and idols. The first leads to life and prosperity. The other gets you thrown out of the land and leads to destruction.
He prefaces this by explaining, this word, this choice they are being given, is not some deep and mysterious thing to ponder. It isn’t some riddle whose answer is hidden in heaven or some that is hidden in some distant foreign land across the sea. It is right here. You know what it means to choose God and you know what it means to disobey. No tricks, no riddles, no mysteries.
Paul uses these verses to convey the same ultimate message. You know the choice. You choose. Accept the truth that God raised Jesus from the dead and He lives and confess that with your lips. Or, don’t. No tricks, no riddles, no deep philosophical diatribes, no mysteries. You choose.
He goes back to Moses discussion of the law when it was given. It isn’t something we must climb to heaven for or something that we must cross a great divide. It is something that is near to us, it is in our mouth and our heart so we are to proclaim it (see Deut 30:11-14)
Believe in their heart and confess with their mouth
You will be saved: salvation will be bestowed upon you as a gift from Jesus who alone can provide it
Believe with your heart that He paid the price of your sin and overcame death.
Declare with your mouth what is in your heart, Jesus is Lord (including Lord over me)
This is the only way.