God is love — walk in the light, love one another
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life.
1 John 5:131 John is the letter of assurance. Written by the apostle John around 90 AD to combat early Gnosticism, the letter addresses the question: how do I know I am saved? John gives three tests: doctrinal (believing Jesus is the Christ), moral (keeping his commandments), and social (loving the brethren). If you believe rightly, live rightly, and love rightly, you have eternal life. The letter is warm, pastoral, and emphatic. John writes as an elderly father to his spiritual children.
The structure is cyclical — John returns to the same themes repeatedly, each time from a different angle. Walk in the light (1). Love not the world (2). See what manner of love the Father has given us (3). Test the spirits (4). God is love; we love because he first loved us (4-5). Whoever believes has eternal life (5). The letter does not follow a linear argument. It is more like a spiral, circling the same truths: God is light, God is love, Jesus is the Christ, walk in truth, love one another.
The theological heart is God's nature: God is light (1:5), God is love (4:8, 4:16). And the incarnation: the Word was made flesh (1:1-2), Jesus Christ is come in the flesh (4:2). The Gnostics denied Christ's true humanity. John insists: we have seen, heard, and touched him. He is fully God and fully man. The tests of genuine faith are clear: confess Jesus as Christ, keep his commands, love the brethren. If you have these, you can know — not hope, not wish, but know — that you have eternal life.
2 chapters per day
'If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. If we say that we have not sinned, we make him a liar, and his word is not in us.' The person who claims to be sinless is either self-deceived or a liar. The Christian response to sin is confession. God is faithful and just to forgive. Not merciful and gracious (though he is), but faithful and just. Why? Because Christ paid the debt. Justice has been satisfied. God is just to forgive those who confess because the penalty has been paid at Calvary. Confession does not earn forgiveness. It receives what Christ has already purchased.
'Beloved, let us love one another: for love is of God; and every one that loveth is born of God, and knoweth God. He that loveth not knoweth not God; for God is love.' Love is not just what God does; it is what God is. God demonstrated his love by sending his Son to be the propitiation for our sins. We did not love God first; he loved us first. And because we have been loved, we love. The command: love one another. The test: if you do not love, you do not know God. You can claim orthodoxy, but if you hate your brother, you are a liar. Love is the proof of regeneration.
'These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God.' John writes so that believers can know — not hope, not guess, but know — that they have eternal life. This is assurance. And it is based on objective truth, not subjective feelings. If you believe Jesus is the Christ, if you keep his commands, if you love the brethren, you have eternal life. The evidence is clear. The promise is certain. You can know.
'God is light, and in him is no darkness at all. If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: but if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.' This is the first test. God is light — morally pure, fully revealed, utterly holy. If you claim to know God but walk in darkness (sin, lies, immorality), you are lying. Fellowship with God requires walking in the light. This does not mean sinless perfection. It means living in honesty, repentance, and obedience. And when we do, Christ's blood continually cleanses us.