As John writes to his brothers and sisters in Christ in Ephesus, you can hear in his heart a desire to build up rather than beat up these friends in the faith. There have developed a group of pseudo-believers who have left the church and are now claiming to have a superior knowledge and experience with Christ. John wants to further press into those who remain that their faith is genuine. Their master is no longer sin, their master is Jesus.
1 John 3:1-10, 1 John 2:28-29
1 John 5:1-12