Christianity in WordNet English dictionary

1. the collective body of Christians throughout the world and history (found predominantly in Europe and the Americas and Australia)
   "for a thousand years the Roman Catholic Church was the principal church of Christendom"
   Christendom  Christianity 
   
2. a monotheistic system of beliefs and practices based on the Old Testament and the teachings of Jesus as embodied in the New Testament and emphasizing the role of Jesus as savior
   Christianity  Christian religion