I've just finished the first section, Questioning Grace, of Spencer's book. "A Heretic's Guide to Eternity." Within this section is a rather large bulk of material that develops a contrast between religion and spirituality. (Most direct summation on pages 58-60)
In a very real sense the contrast creates what I believe to be an unintended false dichotomy between the two. The terms Religion and Spirituality become locked in binary opposition with the clear preference being spirituality. This contrast sets up a reversal of the current social preference yet does not decenter the core dichotomy. I think the interplay of Religion and Spirituality is much more complex than the contrast painted within the text.
Religion is a social codification of spiritual experience(s) into an explanation that others may utilize as a guide within their society. Without a Religious framework to express your spiritual experience in, your communication is hampered within society. It is this very need to share our Spiritual experience that leads to the creation of Religion over time.
In any society, religion and spirituality are necessary as the one cannot exist without the other. If there is no contact point between the Spiritual experience a person has and their society, they risk being view as either as a madman, lunatic or worse yet a heretic.
Religion exists to foster the social communication of spiritual awareness and experience within a society. Ironically, the seeds of Spiritual experience begin to reside within the social codification of the religious experience. As Spencer notes in his text, the problem arises when the resulting religion is co-opted in order to control or administer the faith to society.
The institutionalized faith will seek its own preservation and social influence. (Just look at the Religious Right in the American experience.) It ceases to be a communicative metaphor or guide to help people experience the sublime nature of sacred reality. At this point, a Religion becomes toxic to the seeds of spiritual experience and awareness that it contains.
Once a faith has been institutionalized, like American Christianity; the communicative metaphor of the institution looses contact with the larger social context. That religion will become increasingly irrelevant to a societies continued codification of spiritual experience. Many people will leave the faith behind or explore other faith systems and religions whose communicative metaphors speak to their (and societies) spiritual awareness and experience.
Yet the decline of a religion does not completely eradicate the hunger for the underlying spiritual experience contained in it. Within the religion, people still manage to nurture the seed of the faith and grow despite the toxicity of the institutionalized form and structure. Over time, these people will either seek to reform the religion or depart from the institutionalized structure in favor of a new expression of the faith.
The emergent church may be just such a move within Christendom today.