According to some Religions, every other Religion, outside of theirs is "Pagan" whether the followers of those Religions agree, or not.
"Paganii" is a Roman/Latin word to describe Folk who do not subscribe to the "Popular Religions" which dominated the Cities.
Pagans, or "country Folk" would Worship as they pleased, with no Tithes, Taxes, or fat lazy Priests. They would give to the Ancestors, Spirits of Place(Rivers, Springs, the Moon..), instead of Humanised Gods like Jupiter(Zeus), Mars(Ares),Mercury(Hermes), which had large Temples in the Cities, and were a source of revenue, tourism, and control, rather than any Spiritual benefit.
Pagans nowadays tend toward Natural Spiritual Belief, as in the Earth Mother, and the processes of the Seasons, and our Journey through Life.