My sorting scheme is based on the particular beliefs of Liberal Religion. Religious liberalism is not defined by particular beliefs about God, Jesus, salvation or sin. Religious liberalism is defined by its theology of religions: where do religions come from and how do they co-exist.
Liberal Religion is defined by three distinct beliefs. (1) The world's religions are human cultural creations (2) no one religion is more true than another and (3) the value of a religion is the effect that it has on those who practice it.
You have to be a religious liberal to be a Unitarian Universalist, but you don't have to be Unitarian Universalist if you are religious liberal. Why? There are all sorts of Religious Liberals in many religious traditions, and many of those who don't affiliate with any religion have liberal beliefs about religion.
Unitarian Universalism is a particular form of religious liberalism. We are derived from Protestant Christianity but have become broader than that and have a distinctive history, customs and set of shared attitudes. But individuals define themselves in or out of our faith identity. Our goal is to be as inclusive as possible to all persons who are religious liberals of any culture and background. We are only partially successful in that ambitious goal.
So the boundary between ourselves as Unitarian Universalists and other religious liberals is necessarily fuzzy and indistinct. Other religious liberals are our closest allies and friends.
Beyond the religious liberals are the many people who share many of the social concerns of religious liberals, but who are not, themselves, religious liberals. We make coalitions with them and cooperate in works of service and advocacy. Habitat for Humanity is an organization of fairly conservative Baptists, who do not believe that Christianity is a human creation, and no more true than Hinduism. UU's will build houses with them. Many African American Christians with whom we share many concerns are not religious liberals. Many of our partners in the Industrial Areas type organizations are not religious liberals.
There are other religious people who are not religious liberals, and who do not share our social concerns. Yet, we are comfortable gathering with them for interfaith dialogue, and to represent the range of faith communities in our locality. We might cooperate on an Interfaith Thanksgiving service.
And finally there religious people in our communities who specifically reject the principles of religious liberalism, and are hostile to us. They don't want to cooperate with us in any form; some even avoid interfaith groupings with people like us. They actively oppose some of our social stances, such as marriage equality. They are adversaries
So, I have sorted out five piles: (1) Unitarian Universalists (2) Other Religious Liberals (3) Not Liberal But Social Partners (4) Not Liberal But Interfaith Dialogue Partners (5) Antagonists.
The Religiously unaffiliated are quite possibly in any of these piles.