What’s the difference between Christianity and Christendom? I thought they were synonyms.
Let’s consult merriam-webster.com:
Christianity–1 : the religion derived from Jesus Christ, based on the Bible as
sacred scripture, and professed by Eastern, Roman Catholic, and Protestant
2 : conformity to the Christian religion
3 : the practice of Christianity
1 : Christianity
2 : the part of the world in which Christianity prevails
So, unless the person was using the word Christendom geographically, if they
made a distinction between Christianity and Christendom, it is one they made up, most likely to distinguish between their concept of a “good” Christian and
Christians they consider it acceptable to hate. Mind you, anyone who calls
himself a Christian and hates a Christian brother is a liar according to the
apostle John’s first epistle.