The "parting of the ways" discussion is normally framed in terms of the eventual separation from Judaism on the part of early Christ-followers. But what if what we think of as "Judaism" was actually considered part of the Ioudaios (Jewish/Judaean) ethnicity, as Steve Mason argues?
Paul can claim to be a Ioudaios (Gal 2:15), but he states repeatedly that though there is value in being a Ioudaios (Rom 3:1), there is no longer any difference between the Ioudaioi and other nations or ethnicities (Rom 10:12); "Jewish" ethnic distinctives have been obliterated in Christ (Gal 3:28). How can there be a parting of the ways if Paul denies the continuing validity of any "Judaean" ethnic differences? Or rather, hasn't the parting of the ways already occurred for Paul?
On the other hand, Paul continues to use the language of covenant and of Israel. He is committed to the Judaean Scriptures and he worships Israel's God. If, for Paul, there is no longer any validity in the Judaean ethnos with its ancestral laws, its temple, its lineage, how does he understand his own sense of continuity with the Scriptures and the promises to Abraham? And how would his movement fit into the spectrum of Graeco-Roman categories?