1 John 1:5-7
5 This then is the message which we have heard of Him, and declare to you, that God is light, and in Him is no darkness at all. 6 If we say that we have fellowship with Him, and walk in darkness, we lie, and do not the truth: 7 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 cleanses us from all sin.
Here’s a great passage by the disciple whom Jesus loved—John. John as a writer is very straight forward with his readers or hearers as was the case. John begins with the light. Light is the revelation of the finished work of Jesus. John contrasts two groups. One group is people who are not walking in the light even though they might say they are. The other group is people who are walking in the light. They have a true relationship with Jesus.
It’s believed that John addresses the first chapter to unbelievers and especially Gnostics who had their own ideas about God, such as they believed Jesus to be a phantom. John is telling them that you say you have this relationship with Jesus but your words and actions betray the fact that you really have any relationship with Jesus.
John is not saying here that believers can walk in the darkness and in the light. He is not saying that you can sometimes walk according to the light of the revelation you have about Jesus and sometimes you walk apart from the revelation. You can’t do both. Jesus dwells in you. The light of the world dwells within you and as John said, in Him is no darkness.
Jesus said it this way in John 8:12, “Then Jesus spoke again to them, saying, I am the light of the world: he that follows me shall not walk in darkness, but shall have the light of life.”
If you are a believer, you can’t walk in darkness. You have the light of life. You then become a light to the world. This just confirms that believers walk in the light and unbelievers walk in darkness.
And as a bonus, the blood of Jesus cleanses and keeps on cleansing our sins without fail.