Greta Christina - a favorite blogger of mine who writes on "sex, atheism, politics, dreams, and whatever" - writes in her blog today about "How can we make people who are questioning their faith feel that atheism is okay?"
She mentions Unitarian Universalism as a place for "people who have left religion but still miss its ritual and community" and a "non-denominational religion without the need for all that pesky God stuff."
You can read the rest of her article here.
I guessing that the changing social norms surrounding church attendance and changes in religious demographics may affect how "atheist-friendly" our Unitarian Universalist congregations are to those who are "deconverting" in the future.
The social expectation that one must attend church is no longer enforced in the United States - in my "Bible Belt" town, most of my neighbors do not attend church regularly (based on the numbers of folks observed doing yard work and other stuff on Sunday mornings).
Christianity is currently the majority religion but it's shrinking. The "atheist/agnostic/unchurched "demographic is growing. Check out the "American Religious Identification Survey" findings for more details about these demographic changes.
Both of these demographic trends and the non-mandatory nature of church in our society will affect our future demographics and future growth. I suspect that our atheist, agnostic, and unchurched neighbors will stop joining us and create their own institutions for supporting their families like the "Atheist Sunday School" mentioned on my blog and in Time Magazine.