Why would people follow the Anti-Christ, or a similar figure? I can imagine some would follow him out of fear, some out of a desire to hurt others, and others out of greed, but what other reasons might there be? I need to think of at least one more reason for people to follow such a figure for my scenario to work, any thoughts?
Following an Antichrist, in the Christian eschatology, fundamentally makes no sense - since he's fated to lose. The outcome is already determined, and his very existence would prove that enough of the rest of the eschatology is true that the only rational course of action is to immediately do everything you can do to become a Christian saint; just by existing, he proves that heaven and hell exist, that eternal damnation exists, etc. It elevates Pascal's Wager into a sure thing.
For your purposes, you would need some reason for the followers of the Antichrist to think that it's possible for him to win. This might require you to create some sort of gnostic or apocryphal alternative Bible, the existence of which has been concealed, which contains the "true" story and some explanation for why the Book of Revelation is a deliberate lie, etc. That way, you could have characters who are following the Antichrist figure because they think he's fated to win, or even because they think he's right.
Lot's of reasons:
The anti-Christ or their representatives convince others that they are totally not evil, simply misunderstood or misrepresented by the powers that be that are the "real evil".
The "good-guys" have a puritanical belief in eternal damnation of sinners that drives people away, why not worship the anti-Christ if you're already being sent to hell for some trivial reason like eating on the wrong day or accidentally lying a few times.
They are simply A-moral and believe that there's nothing wrong with turning to the "dark side". while this is certainly cynical I have met people with similar mindsets.
Good old fashioned mind-control or "corruption" think the dark-side in star wars, the one ring from LOTR or chaos from WH40K.
the anti-Christ claims to represent evils which are while enjoyable ultimately necessary for universal balance. For example many people believe that god allows evil to exist so that it might better serve help us appreciate the light perhaps if people in your world also see things this way perhaps they will support this anti-Christ as a necessary evil. Alternatively it could be a literal cosmic balance that must be preserved for existence to work.
They wish to use anti-Christs powers for good, foolishly assuming they can harness them for positive change rather than getting wrapped up in the whole "soul loosing" thing. This would probably work best if the "Christ-Christ" is distant and not a lot of help, and if people have the capacity for idiocy (just checked yep people are still often stupid).
if you would like any elaboration on any of these points just comment below.
The people do not necessarily realize he is the antichrist. Theoretically, the antichrist could be an individual who appears to actually be Christ himself or a similarly godly figure.
Perhaps your antichrist tells people that they must follow him to escape eternal damnation. That's a very powerful incentive for doing whatever he says regardless of apparent immorality. If the antichrist demonstrates what appear to be miracles or supernatural powers then people will start to believe that he really is a deity (or prophet). When he tells them to murder unbelievers that will seem logical because the people will want to support him in his purification of the earth.
If people still want to save others from hellfire then other immoral acts start to make sense. If forcing a person to submit to dark rituals is the only way to make them convert so they can go to heaven, then families will be willing to let their loved ones go through such processes. If a person keeps speaking out against the guy who says he is god incarnate, then maybe he should be cast out or killed.
The important question is: are the people aware of the fact that they are following the antichrist, or do they genuinely believe that he is a great and good being?
Consider modern Satanists:
Since the Satanist understands that all Gods are fiction, instead of bending a knee in worship to—or seeking friendship or unity with—such mythical entities, he places himself at the center of his own subjective universe as his own highest value.
Satan, or the Anti-christ, is not a literal entity you can play ping-pong with. No gods are. They are representations or abstractions. Jesus Christ (whether once real or not) is now a representation of the values important to Christians: love, humility, getting along as a society, self-sacrifice for others. If a person rejects the idea of putting the welfare of random strangers before his own (Luke 6:30 - Give to every man that asketh of thee; and of him that taketh away thy goods ask them not again.) that person might instead choose to follow an abstraction that better represents his own values - like the AntiChrist. This person might seek the company of like minded individuals who will understand his choices and share his values.