This question began as thoughts from the discussions about UU chaplains and Transient and Permanent's question, Do Unitarian-Universalist Ministers Have a Calling? , and finally crystallized while rereading notes from a writing class. What made the penny drop was a lesson about "the story question". If you haven't had that class, it goes like this: your book can be broken down to a simple question and a simple answer- just two simple sentences... if it can't, it's too complicated to handle in a readable book. It struck me that this lesson- very difficult for a beginning writer, believe me- carries into life as well.
The simple question for a faith- NOT the religious organization, but the faith itself- is "what is your mission?" Most faiths, it seems to me, can answer with an equally simple sentence. For Christianity, it would be "To save your soul from eternal damnation." For Buddhism, it would be "To awaken you to the causes of your suffering." For many NeoPagans, "To reunite you with the natural world you have separated yourself from." Others might say things like "To achieve balance with the universe", "To connect with God".
What is the mission of Unitarian Universalism?