Verse 6 describes the state of the false professor.  He gives the lie to his pretensions of saving faith by continuing to live in the same darkness of sin and uncleanness that characterized him before he became religious.  But set over against him is the happy condition of the man truly renewed by the Spirit of God.  Those who walk in the light, as God is in light, have fellowship with their fellow believers around the holy doctrine of the apostles.  These are they who rejoice in Christ Jesus, and have no confidence in the flesh.  These are they who have taken up the cross to follow Christ.  These are they who mortify the deeds of the body, and live through the Spirit.  Those who are walking according to the light of God’s revealed word, striving through the power of the Spirit to mortify sin and walk in newness of life, these are they who are in the light as God is in the light.  They have come to the light that their sinful deeds may be reproved, and that they may learn to walk pleasing before Him.  They have fellowship with other like-minded believers, who have put their trust in Christ and are walking with Him.  It is indeed a happy thing to enjoy fellowship with the children of God.  Concerning those who show no interest in fellowship and communion with the servants of Christ, it is extremely doubtful whether they are in the light at all.  As “birds of a feather flock together,” so do those come together and rejoice in the truth of God whose hearts have been renewed by the Spirit of life.

But we have not just the privilege of fellowship with like-minded brethren.  This were no help at all were our sin problem not accounted for.  But John says that they who are walking in the light and delighting in the fellowship of the saints have been cleansed from all sin by the blood of God’s only begotten Son.  This is the center of our fellowship, and the reason we have power to walk in the light.  The Scriptures declare that the blood of Christ purges our conscience from dead works to serve the living God.  Without that blood, we may have an interest in trying to serve God, but a bad conscience would keep us from ever doing so with any effect.  No man can acceptably serve the God of heaven and earth whose record and whose conscience are still stained with the guilt of their misdeeds.

One thing this verse does is free us from the notion that it is our walking in the light which makes us acceptable to God.  We do not of our own free will decide one day that we will stop sinning and begin serving God, and then earn His acceptance by our good efforts.  No, the apostle would have us to learn that we never could walk in the light if our sins had not been cleansed.  We walk in the light because our sins have been cleansed, not in order thereto.  The apostle Paul was of the same mind, for after declaring that we are saved by grace through faith, he says, “For we are His workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them.”  John is not giving us “walking in the light” as a means of procuring salvation.  But rather, as his epistle will amply demonstrate, walking in the light is the evidence that the blood of Jesus Christ has cleansed us from all sin.  It is the evidence that we know God, and are known of Him.  In short, John would have us to know that they who walk in darkness have never had their sins cleansed, and are still in peril of eternal damnation.