Are you talking about Joseph Campbell, the comparative mythologist? So which half of Romans are Christians supposed to dismiss as repudiated by Paul? And what are the indicators there are these two voices and that one of them Paul is supposed to be disagreeing with even though he's doing all the talking?
Sounds like desperate harmonizing to escape from the archaic dubiousness of Paul's theology. Of course, the obnoxious part I'm talking about is mainly Paul's set up for the gospel (the presupposition of God's existence based on his small-minded cosmology) plus that gospel itself (Jesus's sacrificial death), which are at the heart of Western Christianity.