John uses the word “darkness” seven times in his first epistle. Assuming that he uses the imagery in the same way he does in the gospel, I surmise that the light/dark language of 1 John is about the conflicts of Judaism/Judaizers and the church.

The first use (1:5) is a statement about God: “God is light, and in Him is no darkness at all.” This means many things, but if we take the light/dark imagery as being primarily about old and new, then John’s assertion is that the character of God has been hidden to some degree in the old world of darkness and now revealed in the new world of light.

John moves immediately from this theological statement to an ethical one: “If we say we have fellowship with Him and yet walk in darkness, we lie and do not practice the truth” (1:6). On the interpretation offered here, John is saying that the conduct of the Judaizers (and/or unbelieving Jews) is incompatible with the character of God. The light has come, and this light shows the character of God Himself. To walk according in the darkness of shadows when the light has come is to depart from the God who is light. While God veiled Himself in a dark cloud, this was OK; but not now that the Lord has emerged in full glory in Jesus.

The other uses of the word “darkness” occur in 2:8-11. Verse 8 claims that the darkness is passing away. Possibly this refers to the world of evil and sin, but two thousand years later it’s hard to see exactly how that world passed away. But if darkness refers to the preparatory stage for the coming of God’s Light, then it makes sense: The true light, Jesus, is already shining, and because of that the darkness of the old system is passing away, though not yet completely gone.

Verses 9-11, however, appear to use the imagery in a different way. How is hatred of brothers characteristic of the old covenant? Let me suggest that John, like Paul, is dealing with divisions of Jew and Gentile within the church. Jewish believers refuse to eat with uncircumcised brothers who do not keep dietary laws. They hate their brothers because they remain in the darkness of the old. They claim to be more advanced, more enlightened, more mature than the Gentile newcomers. John says that they are instead darkened, blinded, and liable to stumble. The use of “darkness” here has the double significance of describing the “earlier” period of history, and of making a moral judgment about those who cling to the old.