(“The coming curse, your antichrist, I am the watcher’s eye” – Earl Doherty*)
Contrary to popular belief, the “antichrist” doesn’t make an appearance in the book of revelation. The only mentions of “an” antichrist (it is actually multiple antichrists) is in the epistles of 1 and 2 John:
1 John 2:18
Dear children, this is the last hour; and as you have heard that the antichrist is coming, even now many antichrists have come. This is how we know it is the last hour.
1 John 2:22
Who is the liar? It is whoever denies that Jesus is the Christ. Such a person is the antichrist—denying the Father and the Son.
1 John 4:3
but every spirit that does not acknowledge Jesus is not from God. This is the spirit of the antichrist, which you have heard is coming and even now is already in the world.
2 John 1:7
I say this because many deceivers, who do not acknowledge Jesus Christ as coming in the flesh, have gone out into the world. Any such person is the deceiver and the antichrist.
In historical context, the epistle writer is really talking about the docetists of his day. Those were the ones who thought that Christ had not come in the flesh but was just a phantom or spirit. So for example, Marcion would be considered an antichrist. The writer(s) of these epistles also seems to be railing against adoptionists, those who separate Jesus from Christ. Again, adoptionists were technically Christians who thought that the Christ was only a spirit that had possessed Jesus, such as what was happening at Mark 1.12 (the spirit literally throws him out into the wilderness: τὸ πνεῦμα αὐτὸν ἐκβάλλει εἰς τὴν ἔρημον::to pneuma auton ekballei eis ten heremon). And of course, the spirit leaves Jesus at his crucifixion at Mark 15.37. Even though modern translations say something like “he breathed his last”, the wording that is used in Greek lends credence to the adoptionist interpretation: ἐξέπνευσεν::exepneusen literally means the spirit left him (ex = out; pneu- = spirit). An example of this sort would be Christians like Cerinthus, another antichrist.
But taking the epistle writer at his bare word, without historical context (since people that full stop didn’t believe that Jesus existed at all probably didn’t exist in John’s day), it would seem that modern Jesus Mythicists might qualify as antichrists. They are also people who believe that Jesus didn’t come “in the flesh” but was originally thought to be a celestial being. It might even apply to mythicists who think that Jesus never existed even though they might think that all early Christians thought that Jesus was a real human being walking around Galilee. Much like Ned Ludd or John Henry.
So to me it seems that even though the author of these epistles of John didn’t have modern mythicists in mind, according to a more relaxed version of his definition of an antichrist modern mythicists might be considered antichrists.
* Note, this is just me being funny, not an ad hominem…