I just read an outstanding lecture John Howard Yoder gave entitled "Bohold My Servant Shall Prosper." He takes his cue from Karl Barth (CD IV/2, p. 676ff), who describes the 'Order of the Community' in terms of service. From there, Yoder proceeds to apply the idea of the church as a servant community to the church's engagement in a democratic society. These were some of my favorite excerpts:
“Not only is it assumed to be the case, but it is assumed to be proper, that the position from which Christians think about systemic alternatives is one of having a weighty voice, if not a determining one, in the choices actually made. […] The patterns are so deeply established that despite themselves even many of those who in the name of liberation set out to ‘do theology from below’ tend still to make, at more points than they recognize, the assumption that the meaning of liberation would be simply for the formerly excluded to have a turn on the throne.” (154)
“Thus while holding to a pattern of rhetoric that says that the issue is whether God cares about the political realm and that the answer is yes, what actually takes place is one more form of minority witness from a position of only very modest clout. So instead of projecting the affirmation of power as good and asking who rejects it, let us begin with the affirmation of servanthood.” (155)
“Neither the position of conscientious objection nor that of conscientious involvement can be adequate if taken as a sweeping recipe. Only the insistence that both are open options, needing to be chosen situationally, can permit either to have integrity. Otherwise, the refusal becomes irresponsible or the responsibility becomes unfaithful.” (159)
“…the first question is whether we are willing to be voted down and ruled over by someone else whose understanding of divine righteousness is less clear than our own. If we are, then our democratic confession is authentic. Then our call to the democratically-elected, majority-supported people ruling over us to be more like servants and less like kings is an authentic extension of our life as church and of our Christology.” (160)
**quotes taken from John Howard Yoder, “Behold My Servant Shall Prosper”, in Karl Barth and the Problem of War and Other Essays on Barth, ed. Mark Thiessen Nation (Eugene: Cascade Books, 2003).
Yoder's words here are, I think, a helpful corrective to the political theology of Jim Wallis, Jerry Falwell, and Jurgen Moltmann (juxtaposition intentional). All of these people want to argue that the church must be engaged in politics - Christianity hopes for more than the transformation of individual lives, Christianity hopes for the transformation of the cosmos. And Yoder would agree (indeed, this is what The Politics of Jesus is about).
But Yoder also refuses to concede the proper modes of engagement in politics to those modes that have been defined as normative in our society. For instance, what you do with your vote is important, but that is a small part of politics. The conversation about where we should engage politically within the established political systems of our society is just as important as the conversation about where we should engage politically apart from the established political systems - as in the third quote above, both options need to be on the table in order to maintain a political existence that is both faithful and responsible. Repeated and unqualified affirmations of the need for Christians to be engaged politically can risk the appearance that Christians ought to pick a party (the primary accepted means of political engagement in the USA), which I think is a horrible idea. But I digress.
Above all, living as we do in a democracy where, at least at some level, we get a say in how we are governed, the church's political involvment should be shaped by this wisdom that exceeds even than JH Yoder:
Jesus called them together and said, “You know that those who are regarded as rulers of the Gentiles lord it over them, and their high officials exercise authority over them. Not so with you. Instead, whoever wants to become great among you must be your servant,and whoever wants to be first must be slave of all. For even the Son of Man did not come to be served, but to serve, and to give his life as a ransom for many.” (Mark 10:42-45 TNIV)