Can God Enact Something New in our Midst

I'm getting ready to participate in a panel discussion next week at the Rochester College Streaming Conference.  This panel discussion will focus on Walter Brueggemann's book The Practice of Prophetic Imagination: Preaching an Emancipating Word.   I'll be saying more later, but as I near the conclusion of the book and reflect on the nature of "prophetic preaching" and the way in which we tend to interpret Scripture in Enlightenment categories that limit God's ability to do the so called "impossible," we end up, it seems to me, focused on what we can do.  So, here Brueggemann, who has been in this section of the book ruminating on Genesis 18:13, which speaks of Sarah laughing at the prospect of bearing a child in her old age -- Can God do what we deem impossible?  Can God create something new in our midst.  So, here we read Brueggemann, who writes:

It was the task and the opportunity of the prophets, the ones with poetic imagination in ancient Israel, to give a forceful “yes” to Israel in its displacement: Yes, YHWH can and will work an impossibility on behalf of the future well-being of Israel. I accent the point because very much of our “prophetic preaching” is defined by and limited to urgent social action pleading. It cannot be emphasized too strongly, in my judgment, that prophetic preaching is the enactment of hope in contexts of loss and grief. It is the declaration that God can enact a novum in our very midst, even when we judge that to be impossible.   [Brueggemann, Walter (2011-12-15). The Practice of Prophetic Imagination: Preaching an Emancipating Word (p. 110). Augsburg Fortress. Kindle Edition.] 

Can our attempts at prophetic preaching get beyond simply pleading for social action, but embrace the premise that God can do what is seemingly impossible, so that we can join God in God's work of creating a novum in our midst?

Although I am committed to social justice, and appreciate the work of people like John Dominic Crossan, who explicate important texts, too often I think we end up, in our fear of embracing an interventionist God, ruling out the possibility that God can act in our midst.  We bless our work with the name of God, but we don't really believe that God actually is free to act.  Call me a Barthian if you  wish, but I'm not ready to relinquish the belief that God actually is free to act in our midst!