My fundamental problem with Leithart is that he considers political power-brokers to be absolutely the most important people in the Church, and the attainment of political power by Christians (or the conversion of politicians) to be among the most important things that could possibly happen in the spiritual realm. Reading Jesus’ parables and looking at his ministry, I simply cannot in any way avoid the conclusion that if you care one whit more about the conversion of Caesar than the conversion of a hot dog vendor, you’re doing it wrong.
I think the mistake Leithart and other sympathetic theologians are making is that they’re confusing historical importance with theological importance. They don’t really look at what Jesus defines as important, because if you look at Jesus’ life and teaching the degree to which he simply did not care about the activities of the ruling class is shocking if you are a student of history and, if you are seriously religious, disturbing. Everyone from Mohammed to Marx gives their followers a pretty explicit program of social organization. Jesus does not, and the attempt to find one in his teachings has stumped earnest Christians for centuries
I think if you let Jesus define the Church and set its priorities, what you see in the history of the Church after Constantine is a grievous, sorrowing, utter disregard of passages like James 2:1-7. Looking at the way church authorities ultimately couldn’t risk the lure of political power and prestige makes me sad. I don’t see that as the kingdom of God come to life. It’s a restoration of the Herodian vision of the kingdom of God with a new coat of paint. Every time I read anything on the “political implications of the Gospel,” I get the feeling that if they’re right, Jesus really made a huge mistake by not going straight to Herod’s palace and telling him, “The kingdom of God is here, and it starts with you.”
And just to offend anyone I haven’t offended yet, I do indeed believe that Leithart is being as faithful a Calvinist as a Calvinist can be on this matter.
As a Calvinist who has read (and disagreed with) R. L. Dabney I'd say that it's hard to take offense. I have come to disagree with people who embrace "political implications of the Gospel" for either the left or the right. Orthocuban has blogged prolifically about how a Christian who takes Jesus' teaching seriously is not going to systemically land on either the left or the right in contemporary American political discourse--ordoliberal as he has called it in his case.
But I suggest here that some preachers and thinkers who say that we should not attempt to directly engage politicals have a differen way of waging the same campaign under different marketing. Yep, "engage culture" or "move upstream". Not to say that Christians shouldn't participate in society and attempt to influence it for the better but love of neighbor means love of neighbor, doesn't it? Not merely love of neighbor as a means to an end.
P.S. Kent, not that you're necessarily reading this but I think it's pretty obvious that Jesus was saying there would always be poor people but not that there was nothing anyone could do to help the poor. It's implicit in the conversation that Jesus was saying "You can help the poor later, what this woman has done for me can't be done later." It's impossible for me to look at the passage you're asking about and see the binary options you've laid out. There are plenty of poor people Christians can help and plenty of poor people who just won't believe in Jesus.