Phyllis Tickle has written a very short and superb book that touches on a spotty yet vast array of influences that have helped to forge the current climate in which the church and world find itself presently.
A primary metaphor for Tickle is that of a garage sale. She makes a claim, and then through a variety of choice descriptions, goes on to show that about every 500 years the Church undergoes dramatic changes. The first transformation was under the auspices of Gregory the Great, then the Great Schism, The Reformation/Counter Reformation and now - The Great Emergence. In her metaphor, she suggests that in these transformational times the Church has a garage sale exercise - that is some of the things it has held in high regard for 500 years or so, are re-imagined, seen as not so exciting and put out for sale.
If you'd like to see how Gregory the Great and Grandma are related, or Freud and Fords - this book is for you. It's an extremely concise history of Christianity/philosophy/culture.
Upon painting the background she deals with the questions proposed in her subtitle. The how Christianity is changing is described in two major arenas. The first major change is in the arena of authority. This question, which the reformation/counter reformation sought to nail to the wall, is evidently like jello and no nail will hold it firm. Tickle's observation is that the answer to the question at present in post-modern churches is in the "scriptures and the community."
This is contrary to the reformation/counter reformation. The text of scripture is understood not to be authoritative of its own accord, due in part to seeing it not as a divine prescription, but as a divine story, describing contextual things. Thus one can't simply transfer across times. It also calls into question the counter Reformation projection of community as stemming from a hierarchical model. In the emergence, community is free association networked community, more libertarian.
The question of authority and its answers consequentally deal a death blow to the segmentation of the church world, especially the quadrants of description or the distinctions of separation. She describes how a Robert Webber, could teach at conservative Wheaton College and yet be a liturgical Anglican, or how a Rick Warren could be a leader in social justice issues.
The old distinctions Tickle sees as being significantly marginalized and in effect being a counter weight of necessity to the emerging world.
I loved reading this book and would recommend it to you.