Many critics and analysts are very concerned with what drives and motivates the emerging church conversation. Recently, one critical article spoke of the emerging chruch being "driven by disappointment" with modern and traditional churches. I also read a scholarly paper which listed "reactionary" as one of the weaknesses of the emerging church. I might be alone here, but when I hear that emergent leaders and thinkers are disappointed with and reacting to modernity, I say, "so ... and ..."
We should be disappointed with the church in modernity. What did it do? Much of it capitulated to the winds of scientific triumphalism and ended up giving up the historic faith. The rest of it, in its hell-bent effort to "stand firm," got mean and cranky, denying the spirit of the same faith.
We should react to these changes. The emerging conversation encompasses many of the "confessing" movements within formerly liberal mainline denominations. For an optimistic look at what is happening in Christendom, read Thomas Oden's The Rebirth of Orthodoxy. It is a breath of fresh air. So is the attitude of those whose concern for tolerance has led them to speak and write kindly about their theological opponents. Brian McLaren, for instance, impresses me over and over with his irenic spirit. I think he is off base on some of his theology, but his spirit is so kind and gracious that I am put to shame reading him.
Furthermore, I would challenge anyone to point to a movement within Christianity that wasn't reactionary. Christianity itself was a reaction to Judaism's treatment of Jesus. Paul and John's writings were reactionary to gnosticism. The Eastern and Western churches reacted to one another, leading to the big split. The Reformation was reactionary. Fundamentalism was reactionary. Evangelicalism was reactionary. So, the emerging church is reactionary - how is that a bad thing?
Once again, the drive of the emerging church is its defintion - to live the ancient Christian faith in an authentic way in the midst of postmodern culture. If that means changing the way church was done in modernity, so be it.