1 John 1:7
But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.

Walking implies a continuing effort. It’s something that involves a consistent action, and so when Scripture speaks of walking in the light, it means that we are to continue taking step after step in the light. The light of the world is revealed to us as Jesus Christ in John 1:9-18. Walking in the light means walking as Christ walked: always yielding to the will of his Father, always glorifying God in all he said and did, and faithfully ministering through word and deed.

As we walk in Christ, we see that one of the results is fellowship with one another. The implication here is that if we seek fellowship with each other apart from Christ, we will find it an impossible task. How can wicked, self-seeking hearts be unified? How can those most concerned with pleasing themselves ever join together in unity? Only those who have seen the light of Christ, and who now live to please God, can experience true oneness.

But what is it that brings people from all different backgrounds together? What can unify those who have such different personalities, such unique gifts, and such varying opinions? It is the blood of Christ. We are unified, not by anything in and of ourselves, but through Him. God’s chosen people are part of one family specifically because we are chosen by God. Salvation by grace, through faith, is the only thing we all have in common. And it brings perfect fellowship.

Only the blood of Jesus can ever truly cleanse us from sin. Jesus is righteous, and offered his sinlessness in exchange for our sin debt. His sacrifice was pleasing to God, and God’s wrath was appeased by being poured out on Christ. On the cross, as Jesus bled and died, he did so to provide our salvation. There was no other way. This is what the writer of Hebrews was referring to when he said “without the shedding of blood there is no forgiveness of sins.” [Hebrews 9:22]