Written by John the Elder to house church believers, 1 John, 2 John, 3 John echo the gospel of John. They emphasize that God is light and love and every true believer will demonstrate God's light and love. Each book also addresses deceivers, teachers who no longer acknowledge that Jesus is the Messiah or Son of God but spread fear and division among believers.
All legitimate teachers will share the truth about Jesus and the cross, love others sacrificially and spread love and light rather than fear. He also reminds believers to welcome true missionaries who teach the message of the cross and love others. They should not welcome deceivers or make idols of anything that exalts itself in God's place.