Jonathan Clatworthy discusses liberalism on his website, related to a book.
For me, the word liberal has become one of those plastic words that is in danger of losing communicative meaning. The Conservative Party at present is fond of using the word liberal. It means, presently, something like social liberal, whereas in the 1980s the Conservative Party had ditched its "one nation" Conservatism for Manchester or Economic Liberalism. The liberalism it now uses it is stealing from the Liberal Democrats, as it is a watered down version of the liberalism of Jo Grimond. That was an intensely local, communal, social liberalism, and at one point even Tony Blair wanted to pull the progressive Liberal political tradition into his big tent. If the conservatives follow through accessible or open primaries then actually it is following the liberalism that forms the ideology of the Liberal Democrats. The Liberal Democrats also inherited the intellectual social democracy once of Labour, but (hopefully) not its centralist tendencies.
In religion the word liberal has arguably an even looser use, or at best an untidy use.
One use is to be liberal about something. So whatever happens to be the thing in play, to be a liberal is to be a liberal in relationship to that. This is what is often meant by liberal Christianity. It is rather difficult to use this across the religions. What is it to be a liberal Hindu, for example, or a liberal Buddhist? So the liberalism is a relationship to a dogma or a received tradition somehow fixed.
Another use of liberal would be something like the Socinian use, a commitment to a process of reasoning. So you receive the given text, and that text is the evident material in front (with all its contradictions and variations) and even if the text is revelation in basic reception it is reasoned out for understanding. This is what the Church of England means when it refers to the Liberal tradition it receives along with the Evangelical and the Catholic.
Being liberal also means relating to the naturalistic, ordinary, secular even, ways of common understanding and importing these into a religious tradition. This is not about reason as such, or as a process, but the sociology of knowledge about how we assume thought. It is about how being technological affects thought. For example, if rain is coming we no longer give that divine meaning or interference, but just think in terms of weather charts. If we have a problem, our technological culture tells us that we make solutions. Praying is beyond plausibility.
This further extends into the culture of social trends, so to be liberal is to connect with the variety of definitions that arise in the secular and ordinary world about being human - how we, so to speak, paint our faces and wear badges. This overlaps with the naturalistic (biology, chemistry, physics, maths), but it makes the naturalistic ideological too.
Also being liberal is to be liberal constitutionally. This means rejecting creeds and instruments of power - authority is purely consensual and earnt. Some institutions have limited liberal elements, for example checks and balances in power can be a liberal element or a relaxed view of creeds. The authority given to decentralised theologians can be a liberalising element. Some institutions are thoroughly liberal, for example in rejecting creeds, any central power and having no belief conditions of membership. Nevertheless, even in constitutionally liberal groups (Quakers, Unitarians) concentrations of power can emerge (e.g. at the congregational level). Inevitably the constitutional liberal is dealing in a market place of ideas and building from the bottom up. There is plenty in the religious culture, but not so co-ordinated as was, so is more like a 'homeles mind' and making sense of old and new religious symbols is quite a task every time.
Another form of liberalism is consumerist New Age religion, at least in as far as it represents choice across different purchasable forms. You may also pay your fee and do one thing, and pay your fee and do another thing. The actual forms themselves may be supernatural, superstitious and magical, even authoritarian.
For myself, I am a constitutional and process liberal, and of course think naturalistically and according to the sociology of knowledge. I no longer say creeds, nor take communion, and by removing the Anglican label I also declare that, say, the Bishop of Lincoln is not my bishop. He is nothing to do with me. He might have a lot to do with a church I walk into, but I do it freelance. By the way I suggest he is 'liberal-about-Christianity.'
The claim I want to make is that inevitably the ethical will be located within the sociology of knowledge of what is plausible and in naturalistic thinking. This means that where a tradition is set up against plausibility and the naturalistic, e.g opposes 'human rights' as inadequate, then the tradition will veer towards being unethical. Ethics are located in who we are in a simple and straightforward sense, but also in ideas that are part of the naturalistic outlook. Talk about a man as a God and virgin births or coming back to life seem to exist in another realm.
Some think that being liberal means being open minded to the point where the rejection of some things ought to be reconsidered. This is the worst use of liberal: once something has been reasoned, once something is worked through, that's that unless there is new evidence or argument to the contrary to then be reconsidered. But that is the process of liberalism and this other possibility is the inconclusiveness of any conclusion.
Just to have a tradition and follow it in the manner that it becomes its own policeman seems bizarre, but this is what Rowan Williams does - and indeed in some cases he is so buried inside the Bible and narrative detail that he forgets today's sociology of knowledge and plausibility. Reason does not mean working out the tradition - that is what the tradition does. Nor is it about constructing a narrative of the Bible, because that is what the evangelical does. Reasoning is not subservient to a greater task and is thus reduced in scope. It always stands under its own rules that expand its scope.
Bishop John A. T. Robinson of Honest to God used to reason, except he would be dogmatic when it came to the incarnation. He thought there was a necessary and vital task for the Church to find the argument for it. Not the argument about it, but already in favour. But folks since like Don Cupitt and Richard Holloway are fully liberal (despite Cupitt's rejection of the term when it comes to liberal-about-something theologians) because they pursue religion within plausibility, naturalistically, and in a method where everything is subject to discussion and debate from the bottom up, not as in a tradition of top down where debate is to affirm or continue the whole tradition. I'm with Cupitt and Holloway.