First, this would seem to make the theology more Jewish than Christian.

Chris, the emphasis in the first place was on continuity with the full biblical narrative, which includes within itself the tension between the old and new covenants. It was really only a way of saying that the emerging church should define a dependence on scripture in narrative rather than dogmatic or systematic terms. It does seem, however, that the emerging church is anxious to recover the Abrahamic (and perhaps ultimately creational) emphasis on blessing. It brings an important social and environmental dimension to ‘mission’.

Is the dichotomy between Jewish and Christian a valid one in this context? Paul’s argument in Romans and Galatians would appear to be that the calling of and promise to Abraham persists regardless of whether it takes a distinctively Jewish form or not.

I find myself more inclined to talk about the people of God than of the Church or of Christianity these days. ‘Church’ is probably unavoidable; ‘Christianity’ seems more disposable. There could be several reasons for this - the influence of NT Wright, postmodern embarrassment with Church/Christianity, etc. But it seems to me also to reflect a positive preference for an expression that highlights historical continuity running back to the calling of Abraham to be a people for God in the midst of the nations. My reading of New Testament eschatology also suggests that the crisis of the end of the age of second temple Judaism constituted more a restoration or reformation (with a new king put in place) than a radical break from or repudiation of the Old Testament people of God, but this is obviously more contentious.

And then I found it odd to privilege this particular image – God’s promise to bless Abraham and through his seed to bless the nations – in a way that made it feel more incumbent upon Abraham than upon God.

I’m not sure I get this. How is it less incumbent on God? He actively blesses Abraham and the nations through Abraham. As for privileging this particular image, I would suggest that the eschatological crisis of the New Testament - including the story about Jesus as Son of man, suffering servant, Davidic son - is precisely the recovery of this image of what the people of God is meant to be. Plenty to discuss there!