1 John was written to combat early Gnostic-like heresies that denied the incarnation and separated belief from behavior. John provides tests of genuine faith — believing in Christ's incarnation, obeying God's commands, and loving fellow believers — as the basis for assurance of salvation.
The Word of life who was from the beginning; Jesus Christ the righteous, our advocate; the Son of God who came in the flesh; God's love revealed through Christ