The Light

5This is the message we have heard from him and declare to you: God is light; in him there is no darkness at all. 6If we claim to have fellowship with him yet walk in the darkness, we lie and do not live by the truth. 7But 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 sin.
-1 John

God is light and there is no darkness in Him. What is darkness? Darkness can be seen as the absence of light.
When we walk in darkness, we walk in the absence of light. In darkness, we are not able to see clearly and can probably only stumble our way about. Yet the moment we have light, light reveals what cannot be seen in darkness and because of the presence of light, we are able to see better and notice obstacles or stumbling blocks that were present yet previously unnoticed in darkness. Thus we can avoid these stumbling blocks and walk better.
God is that light and He reveals to us what we were unable to notice in the darkness and through His light, we can walk with full assurance and confidence.