It's pretty sad that people who understand well enough that Antifascist is just a word trick, don't seem to understand that Atheist is the same kind of word trick.
Like Christians like to point out about Satanists - Satan only makes sense as a story as an accessory, and a consequence, not as an original source. Like saying that the winner of a competition is not the point of having a competition.
If you are against fascism, that means nothing. You can still be any other kind of totalitarian without being a fascist. Or national socialist.
If you are against christianity, that means nothing, because there is nothing about christianity in itself that is either venerable, or despicable, yet as an atheist you are presenting yourself as being superior because "you grew out of that".
I think of myself as a Christian, but I don't believe in the Holy Trinity or the crucifixion or any of that.
To me, to be Christian, means to be against the violence of political, banking and military power.
To me it is the utter rejection of any man claiming to be chosen by God. Such men are always seeking to look powerful by squashing and killing other people who make them "look bad".
To me, Pontious Pilate was more Christian than Herod. A pagan roman administrator. The Jews openly demanded a well known criminal be spared well deserved execution.
Does that mean I hate jews? That I am anti-judaic?
Seeing the value of ideas, and in their correct application, is what we are all supposed to aspire to.
But the reality is, the great majority just take whatever they are given, and shun those who think about it. Especially if they don't agree with you about what Heresy means in the contemporary cult of power, whatever form that takes at the time.
To be christian, is always, and ever, to be against that power.