Antichrist

RORY: Oh, right, Jess is the Antichrist, I forgot.

Theologically, the Antichrist is a prophesied figure who sets himself up as a false Messiah, but popularly understood to mean anyone who is an opponent of Christianity, with the motive to destroy or damage the church. It’s also used colloquially to mean a person or thing which is fundamentally evil, and an enemy of everything which is good.