n. 信奉基督教的国家

[ noun ]
the collective body of Christians throughout the world and history (found predominantly in Europe and the Americas and Australia)
<noun.group>
for a thousand years the Roman Catholic Church was the principal church of Christendom

Christendom \Chris"ten*dom\, n. [AS. cristend[=o]m; cristen a
Christian + -dom.]
1. The profession of faith in Christ by baptism; hence, the
Christian religion, or the adoption of it. [Obs.] --Shak.

2. The name received at baptism; or, more generally, any name
or appelation. [Obs.]

Pretty, fond, adoptious christendoms. --Shak.

3. That portion of the world in which Christianity prevails,
or which is governed under Christian institutions, in
distinction from heathen or Mohammedan lands.

The Arian doctrine which then divided Christendom.
--Milton

A wide and still widening Christendom. --Coleridge.

4. The whole body of Christians. --Hooker.