Paul writes - "Our task" as preachers, “curators” (hat-tip to Mark Pierson – see the excellent, The Prodigal Project co-written with Mike Riddell and Cathy Kirkpatrick. In particular see chapter 4, “New Approaches to Worship”), chaplains etc, Walter Brueggemann contends, "is not to construct a full alternative world, but rather to fund - to provide the pieces, materials, and resources out of which a new world can be imagined. The place of liturgy and proclamation is "a place where people come to receive new materials, or old materials freshly voiced, which will fund, feed, nurture, nourish, legitimate, and authorize a counter imagination of the world" (from, Texts Under Negotiation: Bible & Postmodern Imagination).
Rowan Williams, in a BBC interview with Joan Bakewell, said something related to Brueggemann’s point. He said:
“…When I’m preaching I think one of the most important things I can do is to try and touch the imagination. It’s not an instruction, it’s not telling people to be nice; that would be awful. I hope that people will carry away from a good sermon a sense of the world being slightly larger…”