terms are hijacked in the name of kindness or fairness or even sensitivity?
C.S. Lewis in his preface to The Case for Christianity offers insight on a "much less important word."
The word gentleman originally meant something recognisable; one who had a coat of arms and some landed property. When you called someone "a gentleman" you were not paying him a compliment, but merely stating a fact. If you said he was not "a gentleman" you were not insulting him, but giving information. There was no contradiction in saying that John was a liar and a gentleman; any more than there now is in saying that James is a fool and an M.A. But then there came people who said--so rigidly, charitably, spiritually, sensitively, so anything but usefully--"Ah, but surely the important thing about a gentleman is not the coat of arms and the land, but the behaviour? Surely he is the true gentleman who behaves as a gentleman should? Surely in that sense Edward is far more truly a gentleman than John?" They meant well. To be honourable and courteous and brave is of course a far better thing than to have a coat of arms. But it is not the same thing. Worse still, it is not a thing everyone will agree about. To call a man "a gentleman" in this new, refined sense, becomes, in fact, not a way of giving information about him, but a way of praising him: to deny that he is "a gentleman" becomes simply a way of insulting him. When a word ceases to be a term of description and becomes merely a term of praise, it no longer tells you facts about the object: it only tells you about the speaker's attitude to that object. (A "nice" meal only means a meal the speaker likes.) A gentleman is now a useless word. We had lots of terms of approval already, so it was not needed for that use; on the other hand if anyone (say, in a historical work) wants to use it in its old sense, he cannot do so without explanations. It has been spoiled for that purpose.
I know that's a long quote to take in, but it establishes Lewis' point that the word "gentleman" originally conveyed meaning in the information it provided. However, in the name of kindness and sensitivity, some well-intentioned people decided to use the term as praise instead of description.
What happens when the term "Christian" is at stake in its meaning?
Now if once we allow people to start spiritualising and refining, or as they might say "deepening," the sense of the word Christian, it too will speedily become a useless word. In the first place, Christians themselves will never be able to apply it to anyone. It is not for us to say who, in the deepest sense, is or is not close to the spirit of Christ. We do not see into men's hearts. We cannot judge, and are indeed forbidden to judge. It would be wicked arrogance for us to say that any man is, or is not, a Christian in this refined sense. And obviously a word which we can never apply is not going to be a very useful word. As for the unbelievers, they will not doubt cheerfully use the word in the refined sense. It will become in their mouths simply a term of praise. In calling anyone a Christian they will mean that they think him a good man. But that way of using the word will be no enrichment of the language, for we already have the word good. Meanwhile, the word Christian will have been spoiled for any really useful purpose it might have served.
We must therefore stick to the original, obvious meaning. The name Christians was first given at Antioch (Acts 6:26) to "the disciples," to those who accepted the teaching of the apostles. There is no question of its being restricted to those who profited by that teaching as much as they should have. There is no question of its being extended to those who in some refined, spiritual, inward fashion were "far closer to the spirit of Christ" than the less satisfactory of the disciples. The point is not a theological, or moral one. It is only a question of using words so that we can all understand what is being said. When a man who accepts the Christian doctrine lives unworthily of it, it is much clearer to say he is a bad Christian than to say he is not a Christian.
Preserving the integrity of the word by preserving the integrity of the meaning is accomplished by pursuing the integrity demonstrated by Christ. Anything less is the folly of harm.