Kingdom or Christendom
In popular usage, the English term ‘Christendom’ refers to “that part of the world in which Christianity prevails,” either because most of a nation’s citizens claim to be Christian, or because a specific church or denomination is recognized by the State as the country’s official religion. Thus, the nation becomes identified as “Christian,” it is one of the “Christian nations” as opposed to the less enlightened non-Christian peoples and cultures of the planet.