[Update: After adding some consideration of the term 'power-as-appeal', I have substituted the term 'power-as-invitation' for the previously used term 'power-as-persuasion'.]
Thesis 1. Following the examples of Jesus and Paul, Christians should not seek to wield 'power-as-force' over those who are not members of the Church.
This thesis requires some explanation.
(1a) What do I mean by the expression 'power-as-force'? By using that expression I am referring to power that is exercised in such a way that it leaves those on whom it acts no alternative but to comply or be punished — it forces compliance. Power-as-force is the form of power that is exercised by the State through the military, the police, the courts, the prisons, the hospitals, and all the other institutions that discipline and punish the general population (I am, of course, indebted to Foucault in this regard). Power-as-force says to a person: “You must do this,” or “You cannot do that” and “If you do 'this', then we will imprison you” or “If you do 'that', then we will hospitalize you.” Significantly, power-as-force operates on people regardless of their belief-systems. You do not need to ascribe to the fundamental beliefs of the system of power-as-force, you simply must obey or face the consequences.
(1b) When we look to the example of Jesus, we discover that this is precisely the form of power that he rejected. Of course, Jesus did exercise power-as-force over some things:
-nature
-sickness
-demons
-death
-some property, including animals (the Temple incident!)
However, the key thing to realise is that Jesus never exercised power-as-force over any people outside of the community of discipleship. It is only within the community of disciples that Jesus exercises a minimal form of power-as-force (by issuing commands that require obedience).
(1c) We see the same thing in the letters of Paul. Paul is willing to issue commands, and expects obedience from his churches. But he thinks it is a mistake to try and extend that power-as-force outside of the community of faith. Thus, he writes:
I have written you in my letter not to associate with sexually immoral people — not at all meaning the people of this world who are immoral… What business is it of mine to judge those outside the church? Are you not to judge those inside? God will judge those outside (cf. 1 Cor 5).
Paul is not interested in judging those outside of the Church, nor is he interested in holding them to certain standards of behaviour. He is, however, very much interested in engaging in those practices within the community of faith.
Thesis 2. Therefore, Christians should seek change within the world through the Church, which practices 'power-as-invitation', not through the government which practices power-as-force.
Again some explanation is required.
(2a) What do I mean by the expression 'power-as-invitation'? I do not mean the pursuit of 'seeker-sensitive' church models, nor do I mean the ongoing fascination with presenting a 'relevant' form of Christianity. Rather, I understand power-as-invitation to be what comes when the Church models an alternate way of sharing life together. The Johannine material captures this well — we will be known, within the world, by the love that we have for one another (this emphasis also appears in the Synoptics and in the Pauline material). Of course, that love is to be an overflowing love, and just as we are to be known for how we love one another, we are also to be known for how we love the 'poor', and even for how we love our 'enemies'. Such a way of sharing life together does not exercise power-as-force, but it does exercise power-as-invitation, because it is open to others and will appeal to many. Indeed, the term 'power-as-appeal' might be an even better term for this sort of power, as the word 'appeal' implies attractiveness (i.e. “I find that way of life to be very appealing”) but also implies the sort of weakness that is found in begging (i.e. “I appeal to you as Christians”).
(2b) Therefore, rather than imposing demands upon those outside the community of faith (which is precisely what the government does when, for example, it demands that pacifist pay taxes — taxes that will help to fund the war effort), the Church issues an invitation to those outside. Governments demand, the Church invites.
(2c) Thus, we see why Christian involvement in the government is, despite good intentions, and despite whatever positive impact it might have, largely a mistake — a mistake that, IMHO, results from a misunderstanding of how Christians are to relate to power. Simply stated: the government operates by using a form of power that is denied to Christian engagement with those outside the Church, and it is impossible to participate within government without accepting this underlying power structure.