If we say that we have fellowship with him and walk in the darkness, we lie, and don't tell the truth.

 (ii) The dark is hostile to the light. In the prologue to his gospel John writes that the light shines in the darkness, and the darkness has not overcome it ( John 1:5). It is a picture of the darkness seeking to obliterate the light--but unable to overpower it. The dark and the light are natural enemies. 