1 John 1:6 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 cleanseth us from all sin.
These two verse John just tells it like it is. First i believe he is talking about those who act like they have a relationship with Jesus but live their life everyday walking in sin. To walk in darkness means you are a far away from the light. To walk in darkness means you are walking with the devil. No person can walk in darkness and claim to be righteous, that is living a lie and that is sin. Then John gives us the answer on how not be living that lie. He states it simply by letting us know if we will walk in the light of Jesus Christ and associate ourselves with other believers we will be living the life He wants us to live. This is because the of blood Christ that was shed cleanses us from all our sin. We have to make this choice daily and know through faith that He is faithful and just to forgive us.