Paganism comes from the Latin word paganus, which means a country dweller.
When Christianity started branching out into new territories the first people converted were those that lived in the city, as well as the ruling elite. These people, purely because of where they lived were exposed to this new religion first, while their bretheren who lived in the countryside continued with their ancient traditions. The term pagan only became derogatory after Christianity became the dominant religion and in modern times is occasionally confused with atheism-the lack of religious belief. There is also a slight distinction in the term paganism. As I mentioned before paganism is defined as any religion outside of Christianity, Islam, or Judism.