I just read through the First Epistle of John, and I did not get the impression that he is writing about predestination. I got the impression he is teaching the basics of the faith to a group of faithful, those who had been baptized into the Body of Christ, and denouncing Gnostic teachings that said Jesus never came in flesh and other heresies.
shh, shh, shh. Don’t go making sense there...
Pay attention. 1 John is, as I said, about assurance of salvation. I did not say it was about predestination. Read 1 Peter, Titus, 2 John, Ephesians 1, Luke 18, Romans 8 to learn about election/predestination.