I received a complaint from an atheist who occasionally visited the Abraham Lincoln Unitarian Universalist Congragation (ALUUC) in Springfield, Illinois. They were invited to a monthly meeting to what they apparently believed was an organization that was inclusive of all beliefs, but when they voiced their opinions about certain topics they were berated and criticized by ALUUC members.
It is a common misconception that atheists think they could be welcomed into a Unitarian Congregation because Unitarians promote themselves as being accepting of all faiths. The problem with atheism is that it has nothing to do with faith what-so-ever. One must have beliefs that are supported purely by faith and not facts or science to be accepted by any group that claims that it welcomes all religions or that claims to be tolerant of all religion.
Being an atheist means renouncing any claim or belief that is supported by faith alone. An atheist must hold beliefs that are supported only by facts and pure scientific inquiry. Unitarians are busily competing with Bahai to attract believers who are mostly on-the-fence about which faith to pursue. Note to believers: You should probably go to the church where the most powerful political members of your community attend, and it won't be either Unitarian or Bahai, it will most likely be Catholic, Lutheran, Methodist, Baptist or whatever.
There has recently been Unitarian infiltration of atheist groups. The Unitarians are still religious folks, they are just not as fearful of atheists as the more fundamentally religious, but they are much more dangerous as they have connections to the fundamentalists. Get them out of your groups. They are spies.