These four verses could be almost all a Christian needs to know to be a complete, informed follower of Christ. It provides a description of the saved Christian: 1) How we can know we are His. 2) How we can tell if we are lying about it or tell if the truth is not in us. 3) The means (to again) know we are in Him. 4) What this ought to actually look like in the life of the true believer.
1 John 1:6-10
John sums up all he had learned from Jesus in the message: " ... that God is LIGHT, and in Him is no darkness AT ALL." Light in the Scriptures is the emblem of perfect purity, truth, knowledge, prosperity, and joy. In Him, there is NO darkness at all, not even a pin-prick. Where there is pure light, there is pure love. On the other hand, darkness is the absence of light. When people stray from believing in God and having love for others, they step back into the darkness and act in ways that are inconsistent with His character. Darkness represents what is sinful and evil. God is untainted by any evil or sin. Because "God is light" He alone can guide people out of the darkness of sin and unbelief.