Mother Spirit, Father Spirit, where are you?So who or what is "God"? For me, the Divine (as I prefer to refer to it) is not a person, not a thing, and probably not an energy. For me, the Divine is an experience.
In the sky song, in the forest, sounds your cry.
What to give you, what to call you, what am I?
– Norbert Čapek
In Pagan religions, deities have specific names. Some people regard them as energies, some regard them as archetypes; some regard them as individual people. This gets complicated by issues like whether Odin and Woden are the same person. And then what about Thor, Perkunas, Jupiter, Taranis, or even Yahweh - they are all thunder gods, but maybe they are distinct from each other (they certainly are culturally distinct).
In monotheist religions, there are plenty of arguments about whether the "one true god" (TM) is the same as someone else's "one true god". Are the gods of Christianity, Judaism, Islam and Sikhism the same? What about Brahma in Hinduism? What about the Spirit of Life worshipped by many Unitarians and Unitarian Universalists? How far does your concept of "God" extend? If it does not include other deity-forms, should you enlarge your concept? Desmond Tutu has recently written a book, God is not a Christian, making the point that Gandhi's God is the same as Tutu's God.
When I address the Divine in a Unitarian service, I am not addressing Yahweh, or the god of Abraham, Jacob et al (except insofar as subsequent tradition has identified that view of the Divine with the ultimate divine source); I am addressing the Neoplatonic Divine Source, which as far as I am concerned precedes and transcends all other deity-forms.The divine source can be addressed in many ways: "Spirit of Life", "Source of All Life", "Ground of All Being", "Genderless Engenderer", the Tao, "Mother Spirit", "God", "Goddess", "Divine mystery at the heart of all that is" etc. There is even a Unitarian hymn addressed to the God beyond God. These kind of terms can include pantheists, "soft" polytheists, polymorphists, monotheists, theists, Unitarian Christians, non-theists, atheists, agnostics, and maybe a few other theological positions I haven't thought of.
In all of this, I try to keep in mind that the Divine does not exist; it is existence itself, and it's not a person or a thing, but an experience.
I would not use Pagan deity names when leading a prayer in a Unitarian service, because it's not part of the tradition, and because many people join Unitarian churches because they want to get away from viewing the Divine through the lens of personality, whether it's the personality of Jesus or the personality of a Pagan deity. And also, I think it would be difficult for some Unitarian Christians if prayers were addressed to Pagan deities. However, I have addressed prayers to the Shekhinah (the Jewish name for the feminine Divine presence), and read Thunder, Perfect Mind (a Gnostic hymn to Sophia).
I have privately communed with Pagan deities in a Unitarian service from time to time, when I was not leading the service. But mainly, I like the fact that Unitarian liturgy addresses a vague and undefined Divine mystery, and not specific deity-forms. I do think it is important to include feminine imagery as well as masculine and gender-neutral imagery, though.
Does it matter? I hear you ask. Well, it matters to me what I am talking to; and it matters to others, too. I think it is all too easy for people from a monotheist tradition to gloss over these differences.