In fundamentalist Christian mythology, "the Anti-Christ" is another name for the personification of ultimate evil, Satan, the Devil, the Adversary, et alia, which is how I read the term as being used here. Most of the mythology is based on a literal-well-past-the-point-of-foolishness reading of the book of Revelation.

There's an excellent summary of early apocalyptic thinking suggesting an "eschatological opponent" who is to Satan as Jesus is to God.

I don't think I had drawn that connection in the name, so it's possible I'm reading it incorrectly. Though given Trinitarian doctrine, by analogy any adversary could be one such in multiple persons, so the distinction could be a fine one. Chewy.