1 John 1:5 – 7
New International Version (NIV)
Light and Darkness, Sin and Forgiveness
5 This is the message we have heard from him and declare to you: God is light; in him there is no darkness at all. 6 If we claim to have fellowship with him and yet walk in the darkness, we lie and do not live out the truth. 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, purifies us from all[a] sin.
From BibleGateway.com: http://www.biblegateway.com/passage/?search=1 John 1:5-7&version=NIV