A couple of things have made me think of this. Firstly this blog series from my friend Jeremy, which explores a distinction between "radical progressives" and "rational progressives."
There is also this definition of radical, liberal and conservative from Terry Eagleton quoted at Young Anabaptist Radicals:
“Radicals are those who believe that things are extremely bad with us, but they could feasibly be much improved. Conservatives believe that things are pretty bad, but that’s just the way the human animal is. And liberals believe that there’s a little bit of good and bad in all of us.”
What interests me is finding a way to express the tension I feel sometimes between myself and the wider Unitarian movement. One way to express this is to say I tend towards radicalism and the Unitarianism movement tends towards liberalism, but I'm not entirely sure what I mean when I say that so I'm thinking out loud writing this at the moment.
Unitarianism has always described itself as liberal, but what does this mean? It's got something to do with being open to new ideas, believing in progress, tolerating diversity with an incremental agenda for bringing about a better world. And perhaps your assessment of liberalism will depend on what you think about the nature of the world, how reformable it is.
The problem with liberalism can be seen as it's tolerance of opposition. For example there were plenty of Unitarians fighting against slavery (and we rush to celebrate them today) but there were plenty of Unitarian slave-holders, and we never insisted they cease their involvement in the slave trade. We tolerated a diversity of opinions on slavery, because that's more liberals do. This also relates to the econominic position of liberals, who tend to be middle-class.
Or another example: radicals tend to be pacifists while liberals tend to be just war theorists (I'm still working out where I fit with this one). Radicals see war as something so horrific it must be completely renounced, where liberals see war as a possibly necessary evil that must be worked against slowly, possibility fighting a war to prevent war. Liberals see some good where radicals see only bad.
Radicals have a strong agenda for action where liberals want to be open to changing their agenda in the light of new knowledge.
I hope I'm not speaking in stereotypes and generalisations too much.
I'm aware that in many ways Unitarianism can fall into the worse traps of liberalism: well intentioned but unable to build enough consensus on anything to say or do anything very important. We can also in an attempt to be inclusive try to deny our own particularity, history and context, not realising this is ultimately impossible. Andrew Brown has plenty to say about this kind of thing in his own rather philosophically-dense way in places like here.
I'm also strongly influenced by James Luther Adams who (although he also spoke of himself as a religious liberal) emphasised the need for conversion which seems characteristic of radicalism.
So I suppose what I mean by radical is that people and institutions (not least the institutions of Unitarianism) stand in need of conversion (radical change). I am optimistic and hopeful that that change is possible, but not without the death of some things. That change is brought about by understanding our roots and the original dynamism of early movements in both Christianity and Unitarianism.