When I was at Capernwray (Evangelical Bible School in England) our Principal taught us the epistle of 1 John. I will admit first off that it is a very difficult scripture with tons of confusing passages like this:
"Those who have been born of God do not sin, because God’s seed abides in them; they cannot sin, because they have been born of God. The children of God and the children of the devil are revealed in this way: all who do not do what is right are not from God, nor are those who do not love their brothers and sisters." - 1 John 3:9-10
Roman Catholics tend to like Johannine theology and the Gospels best, whereas my background is heavily Pauline. It's important to know where your prooftexts are. Protestants use Romans, we (Catholics) use Corinthians alot (mostly the gospels though). Anyway, 1 John is a mine of Catholic prooftexts like 2:2, 2:29, 3:22-24, 4:8, 12, 5:16 , etc. I'm using the word "prooftext" loosely and maybe equivocally. Basically every religion uses different verses to bolster their points.
But in an attempt at honesty, I have to say I just don't know. St. John the Divine should be called St. John the Confusing. At times he sounds like an American Evangelical Perfectionist / Openly Pelagian to the point that even us Catholics are think: "ok ya works boo faith alone...but remember grace"
I enjoy 1 John because I think ultimately the message is: Christ is the sacrifice for the sins of the world, he did this because he loved us, if we love one another we know we are acting in the Spirit of Christ. But there is ALOT more to it than that, and I enjoy the mysterious nature of this epistle.