The first epistle of John came to people that needed to hear reassurance after hearing false teachers reject the full divinity and humanity of Christ. He affirms the core doctrines of Christianity, saying that we either exhibit sound doctrine, obedience and love in our lives, or else we are not true Christians. Not that we are perfect (1:9), but that we can have assurance of salvation when our lives exhibit holiness and we “walk in the light, as he is in the light.”