Since the comment section of Thomas Kidd’s blog does not work, I will post my comments to his blog article here (his blog article is linked below).
Thank you for your article. If I may, I would like to point out a fundamental flaw in your reasoning without being verbose.
I believe you are linguistically stacking the deck by framing the issue around selective evidence (i.e. the word-concept fallacy).
Christians have been talking about “the Antichrist” from the very beginning because they interpreted Scripture as teaching a future Antichrist personal figure that would persecute the last generation of the church. This is shown in the first Christian document outside of the New Testament, The Didache:
“And then the deceiver of the world will appear as a son of God and will perform signs and wonders, and the earth will be delivered into his hands, and he will commit abominations the likes of which have never happened before” (16:4, my emphasis).
I could cite many more like this in early Christianity, who clearly teach both a future and a personal, individual Antichrist figure; e.g.:
“For all these and other words were unquestionably spoken in reference to the resurrection of the just, which takes place after the coming of Antichrist, and the destruction of all nations under his rule” (5Iren 35:1).
Now, you may claim that the first example above does not use the phrase “the Antichrist”; but then you would be committing the word-concept fallacy, confusing word with the concept. See James Barr’s The Semantics of Biblical Language (ch. 8).
In other words, you are suggesting in your conclusion that Christians did not talk about the concept of a personal eschatological Antichrist figure because the term The Antichrist was not used in most of church history (which is not true in the first place), while at the same time you are limiting your evidence to a single term.
Typically the word-concept fallacy is discussed in biblical texts. But per your argument you can find it in church history. Just another example, Michael Kruger points out when liberal scholars try to argue for a late date of the canon, they focus on the single term “canon,” appealing to the fact that the term “was not used to refer to a list of Christian Scriptures until the fourth century or later” (The Question of Canon, p. 28).
You also assume that in English the lack of an article means that it is not referring to a definite person. My book is titled Antichrist Before the Day of the Lord and yet there is no article in my title, not to mention in the book itself I talk about the Antichrist numerous times without using an article. In the history of the English language, anarthrous ellipsis has been so incredibly common, among other languages as well.
In summary, I believe your analysis and intended conclusion is skewed by excluding important evidence, and thus confusing word with concept.
The notion of the Antichrist is not some recent “dispy” teaching, nor was it some idiosyncratic concept in the corners of church history. The notion of a personal, future, Antichrist figure was the pervasive teaching of our Lord (personified in “the abomination of desolation”), Paul (“man of lawlessness”), John (“Beast”), a host of other terms in the OT, and pervasive in the early church writers.
So to answer your question: “But why do historians routinely assume that sources like this must mean ‘the’ antichrist, even to the point of putting ‘the’ in corrective brackets?”
Perhaps they do this because that was the concept that people were aware of.