I have been writing a talk for Sea of Faith Yorkshire, which was to be called A Sociology of Scattered Progressive Religious Groups but I have since taken the word scattered out, because it also involves some that are part of larger bodies.
It has involved some research and some new thinking, and now it is a stage of pausing and later editing. I am making it available now, because if anyone does see it early, it might actually help absorb some difficult concepts and assist in framing discussion questions. I am sure that some matters have been missed, and some have been skated over rapidly. It is already quite long. Here are the links to the actual talk - it is on my website at Learning - Religion - Academic - Sociology of Progressive Religious Groups, and is provided in an .html version for viewing and a .pdf version for printing.
I intend to provide a summary to help people follow and absorb the talk: this is the summary:
A Sociology of Progressive Religious Groups
Why Liberal Religious Groups Cannot Get Together
A few liberal individuals rather than groups tend to move about. Splits have doctrinal causes.
The word radical is confusing and useless - the qualifier liberal is needed.
Which groups: Sea of Faith largely postmodern that reads, discusses and confers, the Progressive Christian Network (which constitutionally prevents groups joining) that reads, discusses and has an understanding of worship, Modern Churchpeople's Union, that reads, discusses, writes, confers, worships and strategises, the Unitarians and The Quakers, each a full denomination, the inclusive restricted liberalism of the Metropolitan Community Church, the Liberal Catholic Church International, associating with the Liberal Rite (of Unitarian Free Catholics inspiration) and others through the Independent Liberal Catholic Fellowship, and then individual website based creations, plus some groups that have become defunct, and then a need to consider some other faiths. Denominations contain individual liberal churches and have liberal biases, as have some Anglican provinces.
Liberalism can be defined: individualist, also constructed, rights-based, and is divided into liberal about something or liberal constitutionally. Groups can span these in tension (eg Unitarians, Quakers, LCCI). Liberal about facilitates a more in-depth theology than the breadth of constitutional liberalism.
Liberalism relates to systemic or human relations authority, based on large organisation or independent gathering. Some liberal groups show systemic leanings (Affirming Catholicism, Inclusive Church), some human relations (Unitarians, Quakers, LCCI, MCC), and some systemic if in transition (MCU, PCN).
Human relations authority has conserving features, but bipolarity is dangerous. The strongest institution is triangular, of a different 2 against 1, as was the Church of England (which isn't human relations) but it has recently moved to be bipolar and could divide. The UUA is a two by two bipolarity.
Troeltsch included liberalism in his Church Sect scheme by adding "Mysticism". The Church when out of step with the surrounding culture is compromised, today it is the same as a denomination. The cult is a transient, consumerist category. Mysticism involves purely voluntary gathering and reflects the Enlightenment (modernist).
Conversionists recruit by cultural similarity but belief difference (to and from the common culture). After a time a person may mature in belief, read or train, and becoming liberal may move to a church of belief similarity and cultural difference (to and from the common culture). A belief similar but culturally different church can be called an esoteric sect - a sect within a Church, if a Church means anything.
Even Mysticism groups form expectations within, say around the bipolar structures. These form subcultures affecting an overall shape that cannot interlock with other subcultures.
Different groups have their own purposes and functions, that keep them separate from other groups' purposes and functions.
However, individuals can move about, and have multiple memberships.
Yet so much is shared between these groups. Some share diverse and liberal worship forms, some share modernist and postmodernist debates, they can draw on similar past theological traditions (Martineau, Lloyd Thomas). Of course denominations have merged when weak and when arguments are old, but liberal groups tend to be weak even if new.
Soon there may be spillage of liberals as Anglican tensions continue.
Getting together reduces the restrictiveness of traditions but increases plurality, if people can get on together.