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This is always a difficult question because I find that every pagan has their own personal definition of paganism. Some prefer to make it simple by saying that a pagan is a Non- Christian ,in other words ,someone who doesn’t fall upon the Judeo-Christian tree or all non-book religions. This definition can be problematic for two reasons. First it is too far reaching ; it includes Wiccan, Druids, Neo-pagans, Native American , Afro-Caribbean, Dharmic religions ( Buddhism, Hinduism…) and all Non- Christian/ Jewish/ Islam traditions. How many American Buddhists would consider themselves to be a pagan? I would bet good money that this definition was created by the church to lump all non-believers in one category. With that said, I prefer to think of a pagan as someone whose spirituality teaches reverence for Nature and who practices magick and/or rituals. Or anyone who practices any kind of tribal religion. Now my definition includes shamans, Santeria, Yoruba, some mystical Buddhist traditions and so on. But in my experience people who actually call themselves pagans are Wiccan, Witches, Druids or people who have some Wiccan-like beliefs but prefer not to be categorized as such ( perhaps because they want to be free to explore a variety of traditions). Your best bet is not to label anyone a pagan unless that is how they define themselves and to ask them nicely to explain their faith.