John assures the disciples he is writing in 1:1-4 of his first letter that the message they had shared with them about Christ was rooted in historical reality. There were Gnostic influencers who were spreading the heresy that Christ had not come in the flesh (see this in 2 John v. 7). John wants them to k-n-o-w that this is not the case.
He continues throughout the letter to assure them in regard to how different aspects of discipleship—keeping God’s commands (2:3ff), doing what is right (3:10), loving each other (3:14)—all help them to “know” they belong to God. This reaches a pinnacle in 5:13 when he tells then he has written to them that they might know that they have eternal life.
This is all good news for the disciple because we need all the assurance we can get. When we’re with other believers, few of us struggle with security. But when we’re alone, struggling, going through a dark time with our back up against the wall—it’s a different story. We need to know God is with us. The assurance that John writes about is water to a thirsty person.
But it doesn’t stop there.
God’s purpose for us isn’t to bask in our blessed assurance holy huddles while the world remains in darkness. We’ve been liberated to live in the light, so that’s where John quickly moves the discussion in 1:5ff. The Gnostics claimed that since the body was evil, they weren’t responsible for what it did. (That was convenient, wasn’t it?). All that mattered was enlightenment or knowing (gnosis), hence the label Gnostic.
John blows that out of the water when he writes, “If we claim to have fellowship with Him but walk in darkness, we lie and do not live out the truth,” (v. 6). Straightforward speech that leaves no room for misunderstanding. Anyone professing to be a disciple of Jesus who l-i-v-e-d in darkness was lying to others and themselves—no matter how many likes or followers they might have received.
John wants us to understand that the deliverance that begins when we come into Christ, continues as we walk in the light. A lot of important things are in the light. God is the light (v. 5), and therefore in the light (v. 7). Fellowship with one another takes place in the light, as does our continued purification from sin (v. 7).
Living in the light is where life is! Because the Gnostics didn’t take responsibility for the sins committed by the body, they held themselves to be sinless (v. 8, 10). Can you imagine anything sadder than a person in denial about what is obvious to the world? It was Pascal who made the observation that there are only two kinds of people: the righteous who think they are sinners and sinners who think they are righteous. No one who thinks they are without sin is in the light.
Disciples know they’re not perfect, they’re just forgiven and living in the light.