Christendom
noun /ˈkrɪsndəm/
/ˈkrɪsndəm/
[uncountable] (old-fashioned)- all the Christian people and countries of the worldWord OriginOld English crīstendōm, from crīsten ‘Christian’, (from Latin Christianus, from Christus ‘Christ’) + -dōm (originally meaning ‘decree, judgement’).