The two issues of your post seem to me quite closely connected. It has been suggested that Romans 13:1-7 was written in the context of an ‘over-realised’ eschatology: a church, maybe churches, living as if they were already in the ‘new earth’, and there were no responsibilities at all to the ‘old creation’, with its paraphernalia of government etc.; especially where government was associated with the culture’s paganism and idolatry - as in Romans 1:18-32. Rather than an abstract doctrine of the church’s relationship to the state, perhaps there was a particular context which Paul had in mind.

I think there might be a parallel of sorts with the emerging church. The emphasis on organic, closely knit community is probably a long way from political activism. ‘Friends’ is a long way from ‘West Wing’ (I’ve never seen the latter, but pluck it from the air at random as a possible contrast. Come to think of it, ‘Friends’ is a very outdated example. I just couldn’t find a way of weaving ‘Lost’ in - though so far, it has been disappointingly lacking in anything remotely like a cultural subtext. Not that I’ve been watching it. It’s my daughters who are glued to the screen - street cred at school or something of the like).

But what viewpoint are you taking? I assume the ‘prophet, priest, king’ idea is from Calvin, who, I imagine, because I haven’t studied him, saw a close relationship between church and state. From my perspective, church should always have an uneasy and variable relationship with the state.

To take a US example again, I would incline towards the activism of Jim Wallis and the Sojourners commmunity, rather than the politicised religion of the religious right (if such a thing actually exists). I admired the way they were jailed for breaking the perimeter fences of airforce bases in protest against US overseas military policy - while the rest of the church was (apparently) silent, or even supportive of government policy. No doubt the church should also affirm government when its policies reflect the agenda of God’s kingdom (cancelling third world debt? Climate change policy?). But identify church too closely with the state, and you have public burnings of heretics over fires fuelled with green wood. (Calvin again - not on the bonfire, but sanctioning its use).

But where in the US is there a state church (or do you mean ‘state’ as in all aspects of government-funded institutions, such as schools)? The more worrying issue here might be the assumption that ‘church’, ‘faith’, or ‘religious belief’ plays no part in society outside its own institutions. When looking at the extremism exhibited by some sectors of the church, one can understand why. But otherwise, isn’t this a sorry legacy of the enlightenment, and the secular values given to society by those who framed the US constitution?

I don’t personally think that biblical Christianity has the right DNA to govern in any real sense. Our faith was shaped around a summons essentially to faithful weakness in the face of opposition and dominant authorities - and above all under the authority of God. We simply do not have the right calling or the right resources or the right ‘mindset’ to govern effectively. Whether or not Caesar was in any way the anti-Christ, Christ was certainly the anti-Caesar. Christian government is bound to fail - which is not the same as saying that Christians cannot have a significant and constructive role in governments.

I’m not sure how the moral formation thing is going to work if left to the church. Christians aren’t going to agree on what constitutes appropriate moral training. There have been some notably bad examples of Christian moral formation in the past. Do we really believe that the church can be trusted to perform this task well? And other sectors of society are going to want to have a hand in shaping morality - humanists, Muslims, Hindus, environmentalists, celebrities, and so on. How in a western democracy are you going to assign moral formation to the church?

I would suggest that there is a prior question to be asked: What is the people of God called to be in the midst of the nations? It seems to me that two requirements are made of us, are definitive for us: i) to be a dwelling place for the living God in the midst of the nations; ii) to anticipate the renewal of humanity and the created order both in what we do and what we point to.

Once we have established this two-fold orientation, we need to ensure that both are deeply embedded in the life and work of the believing community. They have profound and far reaching implications for both our internal and our external relations. But at the centre, from which all things must flow, is always the point where the theological and the eschatological axes cross, where God gives hope, brings about change, reorients the world towards newness and life - and is worshipped and draws the nations to his light.

The phrase ‘in the midst of the nations’, which is recurrent throughout the Old Testament, matched by the dispersal of the New Testament church throughout the Roman empire, suggests presence, visibility, perhaps vulnerability, access, but also apartness, distinctness. I think the emerging church is going back to the New Testament to look for inspiration, but not so much to the church in Jerusalem with its mass conversions, communalism, signs and wonders, more to the church that confronted the political and religious authorities of the Graeco-Roman world.