John who traditionally wrote the Gospel, 3 Epistles, & Revelation is the only biblical writer to use the word "antichrist" and did not use it in the book of Revelation at all.
John identified Antichrist as a spirit who was already present at the time. The word itself (anti), in the Greek, meant "against" as it does in English, but also meant "instead of" or a "substitute for."
We see this spirit for the 1st time when the Israelites forced Aaron to make the Golden Calf (Ba'al) and he called it "Yahweh" and in modern times when Conservative "Christians" call Mammon, "Jesus."
We see antichrist at work when people claiming to be Christians (Christ-like) substitute teachings of prosperity, selfishness, & easy believeism for counting the cost and picking up the cross of self-sacrifice to live in imitation of Jesus.
The spirit of antichrist is not necessarily "the Beast" of Revelation. As to the "rapture," that is a new doctrine dating back to the 1830s and John Darby and not part of traditional Christianity.