Pagan is an umbrella term referring to any polytheistic religion that centres it's practice around nature(ever religion under paganism is polytheistic but not every polytheistic religion is pagan). Pre - Christian the pagan religion's are some of the oldest in the world and deserve respect.
Person A: Oh yeah, I'm pagan by the way.
Person B: Wait you worship the devil?!
Person A: Umm... No.