An old friend of mine recently asked that question. It's a deceptively tricky question, the longer one thinks about it, especially in the Copy Room of Revelations. It gets sticky of course, because everything does. The spiritual part gets dicey, because you could totally be a Witch and still identify as a Major Religion and go to a Major Religion Service regularly and still practice some version of Witchcraft. Hoodoo (Southern North-American folk magic) is literally built on this. There are no Hoodoo gods. You talk to the gods you came with, who are probably some kind of Christian. You might talk to saints and spirits. But Hoodoo does not have [Goddess Name], the goddess of [Action X]. It is an add on to your American-Christian Starter Pack, though people who don't identify as American-Christian use it too as we are all more shameless versions of The Borrowers in matters of the Craft.
Conversely, you can identify as a Witch and choose to worship only the (Wiccan) God & Goddess pair, the (Dianic WIccan) Goddess and/or a mish mosh pantheon of polytheistic goddesses from various places in the world, some of whom mostly went to sleep for a while (Greek pantheon, Roman patheon, Celtic pantheon, etc) and some of whom never went to sleep (the Hindu pantheon, some fae in Nordic/Celtic countries, the Buddhist pantheon).
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