Christendom

noun

1. the collective body of Christians throughout the world and history (found predominantly in Europe and the Americas and Australia)

   noun.group

   Examples

   For a thousand years the Roman Catholic Church was the principal church of Christendom.

   Synonyms christianity

   Source: WordNet 3.0

2. The profession of faith in Christ by baptism; hence, the Christian religion, or the adoption of it.

   noun

   Source: webster1913