Hi Dicky,
To put it bluntly (as it seems to me), it's a way of making old skeletons dance.
Nice phrase! And yes, that's how it seems to me too.
A great deal has been invested in the Christian belief system, personally and socially. It is still a source for good in many ways. But for those who no longer believe, but feel that they want to belong to some social group or other, and maybe do something good in the world via group activity, then attaching the label 'god' to the focus of their efforts is a way of prolonging the life of such religious systems.
Yes, it smacks to me of "OK, all that religious facts stuff is clearly a busted flush now but if we can't hold the line on that any more, maybe there's some way we can salvage something from it for the feels?".
However, the Christian God who, beyond space and time, brought the universe into being, and who became incarnate in Jesus and went on to die for our sins - this non-realist 'god' sure ain't that at all.
Well no. As I understand it, the irrealist "god" is a label you attach to the way you'd live if there was a god, only there isn't one. Or something. But then it seems to me you've just shifted the problem sideways - what is it about this god that, if it was real, would enable you to live a better life? How would you decide? If you're a loving person anyway presumably you'd live your life as if there was a loving god; if you're a hating person, you'd live your life as if there was a hateful god etc. What then does the notion "god" bring to the party?