What makes a religion pagan?
I'm going to contend that paganisms are preeminently religions of land, lede, and lore.
Land. Paganism is local, intimately related to specific places. Pagans are by definition the People of the Place; when peoples change their place, they bring their mythologies with them, and those mythologies naturalize to the new place. While the term “nature religion” is problematic on numerous levels, the paganisms direct themselves largely to this-worldly concerns, and engage the environment and the non-human beings with whom we share that environment as a matter of primary spiritual course. There are no universal paganisms; or, rather, the paganisms are at their most universal insofar they are most specifically local.