Three different topics in your post; I think the issues are becoming confused. What is ‘this argument’ that you find unconvincing? To what does ‘this’ refer?

As far as Wright’s exegesis of 1 Corinthians 8:6 is concerned, there is the reference to the Shema: “The Lord our God … The Lord is one” (Deuteronomy 6:4) which is now rewritten in the parallelism: “One God - the Father … One Lord - Jesus Christ” (1 Corinthians 8:6).

To continue (quoting from Wright): ” … he has taken the most holy and central confession of (that) monotheism, and placed Jesus firmly in the middle of it.”

Coninuing further: “Paul has taken the word ‘God’ itself and filled it with new content. Or rather, he would say, he has discovered what its true content always was.” (‘What Saint Paul Really Said’/Eerdmans pp.66-67)

Wright also points out that Jewish monotheism of the period was not an ‘interior analysis of the being of the one true God’. It was polemical - asserting that ‘the one God, the God of Israel, was the only God of the whole world’ (and therefore the claims of other gods were blasphemous); and that one day these gods and their powers would be exposed/defeated, and God’s people vindicated.

Following this line of thought, Jesus continued (and fulfilled) the polemic - and by so doing, God revealed more fully who he was. But this is going beyond the immediate point at issue.