I think the first piece of literature — whether it be a position paper, a pamphlet or webpage — I think any new Christian church needs to get down is its understanding of and relationship with non-Christians.
To which I would add, this is also true of Unitarian Universalist congregations. UU congregations actually seem to have 2 or 3 (maybe more) observably different understandings of other religions, including Christianity. For the most part, these theological positions do not even have names, nor even much theological reasoning behind them.
There is a strong strain of old-school supersecessionist Humanism: as modern science burns away all superstition, all religions will eventually be purified into a single ethical humanism.
There is a strong strain of supersecessionist syncretic Unitarian Universalism: all religions will eventually be replaced by a single religion that combines all the best of others into one new world religion.
There is a thought that Unitarian Universalism is a Skeptical Liberal Protestantism that looks world-wide for certain kinds of textual inspiration.
But I agree with Boy in the Bands that nailing this down is one of first tasks of self-definition of any religious body in this here world.