'One' in the Bible

Now I ask you, lady, not as if I were writing to you a new commandment, but [simply reminding you of] the one which we have had from the beginning, that we love and unselfishly seek the best for one another.

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].