Don't render evil for evil, do good instead.
What you have learn should remain in you because you will remain in Christ and Christ is the way
If Christ abide in you, it means the word of God abuse in you and you won't be mistake. If you remain in Christ which is the way, you won't be mistaken
When you choose life, you choose Christ because Christ is life.
After we have received the knowledge of the truth, then you denied, then you are a liar, it's like you deny someone you already known.
If you get separated from Christ, you get separated from Life.
If you are not in the truth, the you are a liar and a liar is the ones that deny Christ, they are anti Christ.
Those that preaches the opposite of Christ are anti Christ. The Catholics, the Manalos church, etc are anti Christ.
If you have already know the truth but you willfully disobey Christ, then that's a sin and you are not of us because of you are one of us, you would stay and remain.
The teaching is to love one another, do the good work then we know you remain in the things that you have known.
For the world to be a better place for everyone of us to live, that is why God commanded us to pay good with good and good with evil no matter what evil someone have done to you because evil will keep following the evil if someone didn't choose to pay good with evil and the world would be hard to live in. Paying good with evil can make the evil doers to join the church of God, they might believe in God through the good that you did towards them.
If you've learn the Christ way, let it remain I you because that is the only way that can save you at the end of the world, if you learn the way and you didn't follow the way, then you aren't save because you already know the way but you choose to go to the wrong side. If you are in Christ, you won't make mistake because Christ is the real way and Christ means life, so you have life if you have Christ in you but you don't have life if you don't have Christ. If you get separated from Christ, then you are separated from life because Christ is the Life
If you deny Christ right after you have known Christ, then there is no remedy for that, you are a liar and you didn't belong among us and you have act like an anti Christ. Those that lie, preach against Christ are those that we call anti Christ; the Catholics and other fake churches are anti Christ.