I don't know. Maybe by not reading it?
... It is a common mistake, however, to associate the antichrist exclusively with speculation about the end of the world. When this mysterious figure first appears, it is not in the apocalyptic visions contained in the last book of the Bible. Rather, it is mentioned a few pages earlier, in two short letters traditionally attributed, like Revelation, to the apostle John. The author condemns those who “do not acknowledge Jesus Christ as coming in the flesh,” explaining that “any such person is the deceiver and the antichrist.” ...
Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time.
-- I John 2:18
And he missed it. Oh well!
I don't think the author was too terribly interested in what I John has to say anyway, only in what he has to say, which I did not find terribly compelling. Read it and decide for yourself.
As for I John, it is obviously mistaken that it was the end of the world, no less than Jesus was mistaken about the end of the world, so these antichrists in I John weren't actually a sign of that, but I John unequivocally took antichrists for signs of the end of the world, and himself believed it was the end of the world.
I John notably has not just one antichrist but many, analogous to the false christs and false prophets predicted at the end of the world in the little apocalypses of the gospels (Matthew 24, Mark 13). And I John 4:1 explicitly states that "many false prophets are gone out into the world."
Both of these things are evidence that in I John's mind the antichrist is connected conceptually to those gospel narratives about the end of the world. That they are also false christs in his mind is proved by the fact that he says that they are docetists who deny, to borrow the Fourth Gospel's language, that the word was made flesh in the incarnation.
So I John is nothing if not speculation about the end of the world, and you'd have to not read it to miss it.
It is also notable that I John does not explicitly use the typical word for sign, let alone any word for sign, that we might expect him to use if in fact he is the same author as the author of the Fourth Gospel, who uses the language of signs like water. This is a little puzzling, but it does not detract from the main point that I John knows from the presence of antichrists that it is the last hour.
Be that as it may, Jesus after the flesh unequivocally repudiated such signs, but the new theology's Christ of faith which sprang up after him didn't just embrace signs.
For it, Jesus was the sign.
And, behold, there was a man in Jerusalem, whose name was Simeon; and the same man was just and devout, waiting for the consolation of Israel: and the Holy Ghost was upon him. And it was revealed unto him by the Holy Ghost, that he should not see death, before he had seen the Lord's Christ. ... And Simeon blessed them, and said unto Mary his mother, Behold, this child is set for the fall and rising again of many in Israel; and for a sign which shall be spoken against;
-- Luke 2:25f., 34
Oddly enough this Jesus grew up to say otherwise:
No sign shall be given to this generation (Mark 8:12).
Sign-seeking and sign-performing were the unequivocal evil business of the devil, this Jesus insisted (Matthew 4:1ff.; 16:1; Mark 1:13; 8:11; Luke 4:1ff.; 11:16).
But the empty tomb swamped that narrative. It only exists side by side in the text which has come down to us in tension with the new narrative which now dominates it in which:
The resurrection became the ultimate sign, the sign of the prophet Jonah (Matthew 12:39; 16:4; Luke 11:29), justifying elaborate timetables for a second coming foretold by signs (Matthew 24:3; Mark 13:4; Luke 21:7); Jesus' miracles in the Fourth Gospel themselves become positively described as signs; Wonder-working becomes the sign of an apostle.
Truly the signs of an apostle were wrought among you in all patience, in signs, and wonders, and mighty deeds.
-- II Corinthians 12:12
The message of Jesus in the flesh by contrast was like a bright flash, exposing the world's utter corruption and proclaiming its imminent transformation. It came suddenly without signs to be observed (Luke 17:20f.), and especially not an antichrist.
The kingdom of God was already there among them, he said, and . . . they missed it.
