Don't you watch movies? Next thing I probably have to define for you is aliens. [sarcasm]

Antichrist: n. 1. An enemy of Christ. 2. The epithet of the great antagonist who was expected by the early Church to set himself up against Christ in the last days before the Second Coming. 3. A false Christ.

Except for number 2 definition, if you are a pretty strong religious person you can call whomever you don't like an antichrist. It might get serious after a little while