Source : Webster's Revised Unabridged Dictionary (1913)

Heathenism \Hea"then*ism\, n.
   1. The religious system or rites of a heathen nation;
      idolatry; paganism.

   2. The manners or morals usually prevalent in a heathen
      country; ignorance; rudeness; barbarism.

Source : WordNet®

heathenism
     n : any of various religions other than Christianity or Judaism
         or Islamism [syn: {paganism}, {pagan religion}]