Heidegger's Bible Handbook: 1 John: Occasion of the Epistle
4. The occasion of the Epistle.
Heretics, persecutors, and hypocrites appear to have furnished for John the occasion for writing. Heretics, Antichrists, False Prophets, 1 John 2:18, 19, 22, 26; 4:1, and Persecutors, 1 John 3:1, 13, are touched upon. Hypocrites also in the bowels of the Church, trusting in an empty profession of faith, were boasting in their ἀναμαρτησίαν/sinlessness, and promising themselves communion with Christ, although devoid of true faith and love.