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.
John returns to the subject of light in verse 7. As he does it augments what he means by the relationship that we have with God. There is a particular characteristic to our journey in the light. That characteristic is that it is, or should be, the same light that God is in, or rather that God produces from himself. In other words, when we say that we are in the light, that we are walking in the light, then what we are saying–or should be saying–is that we are living out and embodying and reflecting God’s love and life in our own.
I think this is what John is getting at in the first half of verse 7. We have to evaluate the source of the light we claim we are walking in. Does it reflect the nature, character, and attributes of God as God is? If not then we may very well be mistaken about the light we are walking in.
The way that John writes, at least for me, it leaves the impression that this is not something we can “sort of” get right. We are either walking in the same light of God or we are not. We are either walking in a way that reflects God’s nature or we are not. Missing by an inch or missing by a mile is still missing the standard that John establishes here.
A good question here is why is getting the issue of the light we are walking in so important? It is important because it will determine who we have fellowship with. If we are walking in different “lights” then we are not walking together. This appears to be a clear implication. If you remove the middle clause we would not know this. “If we walk in the light we have fellowship with one another.” That middle clause creates a significant hurdle for us to address. There is a definite sense that there are many lights out there that wish to intermingle with the true light of God. This cannot be allowed to happen. The distinctive nature of the Christian faith and walk must be maintained. And, how do we do this? We do it by measuring and evaluating the “light” we are walking under.
So, if you are wondering how we will know how to recognize what this light is, I would suggest we look at what John says at the end of the verse. John says that if we walk in the light then the blood of Jesus cleanses us from all sin. The opposite must then also be true. If we do not walk in the light then the blood of Jesus does NOT cleanse us. What then is this light? Should we not think of the Gospel as this light. Dr. John Piper in his book A Peculiar Glory makes a compelling argument that the Gospel is the light that shines and helps us to see the resplendent glory of Jesus. Dr. Piper cites the following passage from 2 Corinthians as the basis for this belief.
4 In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God. 5 For what we proclaim is not ourselves, but Jesus Christ as Lord, with ourselves as your servants for Jesus’ sake. 6 For God, who said, “Let light shine out of darkness,” has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ. (2 Corinthians 4:4-6)
Dr. Piper argues that the parallel phrases in verses 4 and 6 assists us to see that the light that shines is in knowing the Gospel. The “light of the Gospel” in verse 4 and the “Light of the knowledge” in verse 6 are speaking to the same divine revelation. Dr. Piper explains
The parallels help explain the terms. “Gospel” and “knowledge” are parallel because the gospel is the true story of events about Christ and what he accomplished that can be known. In the gospel there are facts to be known…. There is no gospel without historical facts that can be known. ((John Piper, A Peculiar Glory (Wheaton, Ill: Crossway, 2016), 140-141. Emphasis in original.))
Therefore, those who reject or modify the Gospel of Jesus Christ can be said to walk in a different light. When the historicity of Jesus’ life, ministry, death, and resurrection are diminished or undermined we are walking in different lights. Defenses for the historical fact of Jesus being who he claimed and who the Scriptures attest is beyond this post and has been addressed by others. (Some resources I have found helpful include: Lee Strobel, The Case for Christ (Zondervan, 1998) [Amazon]; Gary R. Habermas and Michael R. Licona, The Case for the Resurrection of Jesus (Kregel, 2004) [Amazon]; Ravi Zacharias, Why Jesus? (FaithWords, 2012) [Amazon]; and Josh McDowell, The New Evidence that Demands a Verdict (Thomas Nelson, 1999) [Amazon].)
Based on this verse, one way of identifying the light that we are walking in would be to look around and see who we are in fellowship with. If we will have fellowship with those with whom we have a “common” light, then our friends will tell us a lot about the light under which we are walking. The saying goes “Tell me who your friends are, and I will you who you are.” While this does not tell the whole story, it makes for an interesting introduction.