This should be an interesting set of posts, John! I like the suggestion that the phrase ‘Israel of God’ throws the emphasis on to God’s possession of Israel. But I also wonder whether more could not be made of the argument about Abraham in understanding the force of the phrase ‘new creation’.

In Galatians 6:15 ‘new creation’, as you point out, is contrasted with the duality of circumcision / uncircumcision. Central to Paul’s argument in Galatians is the thought that Abraham’s faith precedes the Law (and circumcision). So does the ‘new creation’ idea take us back to the prior ‘justification’ of Abraham - and does it therefore add weight to the view that Abraham’s family was originally conceived as an alternative ‘creation’?

Paul earlier repudiated the distinction between circumcision and uncircumcision in a similar fashion in 5:6: ‘For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love.’ I wonder if this isn’t also a reference to the faith or trust that Abraham had in the promise that he would be the father of a great people. Notice that it is set within argument about perseverance: ‘For in the Spirit, on the basis of trust, we wait for a hope of righteousness… You were running well. Who hindered you not to obey the truth?’ (5:5-7). Indeed, the whole letter is an appeal to trust the promise that was confirmed by the experience of Spirit - and not to seek to reinforce it by works of the Law. Paul urges them to look for the justification or vindication that Abraham received because he trusted in the promise.

So what I’m suggesting, I think, is that the ‘new creation’ idea does more than define an alternative to the old humanity in which ethnic-religious distinctions reign; it also invokes the creational dimensions of the original promise to Abraham.