'Antagonist' in the Bible

Who is the liar but the one who denies that Jesus is the Christ (the Messiah, the Anointed)? This is the antichrist [the enemy and antagonist of Christ], the one who denies and consistently refuses to acknowledge the Father and the Son.

For many deceivers [heretics, posing as Christians] have gone out into the world, those who do not acknowledge and confess the coming of Jesus Christ in the flesh (bodily form). This [person, the kind who does this] is the deceiver and the antichrist [that is, the antagonist of Christ].