We are all humanists now.
Almost all of the supposedly diverse Unitarian Universalist theologies are humanist reinterpretations of pre-humanist religious movements. Indeed, the Unitarianism and Universalism of the 19th century were reinterpretations of Calvinist Protestantism in the light of the emerging humanism.
The Enlightenment demolished supernaturalism, and when theology now longer described material reality, the purpose of religion turned to serving human happiness and betterment. Religion turned from being God-centered to Human-centered. In short, humanism, in its broadest sense.
This broad humanism was not the same as twentieth century humanism, as summarized by the Humanist Manifesto. 20th century humanism took the path of continued theological realism: the positive statement that there was no God. But other humanists took the path of reinterpreting older religious tradition to serve human purposes.
I’ve been a UU Christian for years, and I assure you that most UU Christians are humanists, reinterpreting Christian tradition to make it serve the human purposes of happiness and betterment. I am sure that there are exceptions.
My sense of other UU theologies are that when there is a conflict between a traditional teaching and the broad humanist purposes of Unitarian Universalism, that part of the tradition is ignored, or explained away, or contradicted.
This is not confined to Unitarian Universalism; this is the liberalizing trend in all religious movements. In fact, “liberalizing” or “westernizing” trends in religion are reconciling orthodoxy with the humanist definitions of reality and humanists understanding of justice: democracy, human rights and feminism, etc.
We are all, broadly speaking, humanists now. Except the fundamentalists, who are not.
What we experience as conflict between humanists and theists in our religious movement and in our congregations are actually narrow and petty fights over language and liturgy. We are not contesting over the TRUTH, or even the beliefs necessary to an ethical life and justice, but over pragmatic issues about membership growth and membership retention: marketing. It all makes us small, not in numbers, but in purpose and concerns.
Humanists now blame the stall in UU growth at our apostasy in turning away from Humanist Manifesto style Humanism. Christians and theists argue that were we more theistic, we will be more relevant to the unchurched, most of whom still believe in God. UU Buddhists point to the growth of Western Buddhism which often lacks a structured community. Let's call these arguments what they are: marketing strategies. Underneath it all, we are all humanists.