1 John 1:5-10
Here is the message we have heard from Christ and now announce to you: God is light, and in him there is no darkness at all. So if we say we have fellowship with God, but we continue living in darkness, we are liars and do not follow the truth. But if we live in the light, as God is in the light, we can share fellowship with each other. Then the blood of Jesus, God's Son, cleanses us from every sin.
If we say we have no sin, we are fooling ourselves, and the truth is not in us. But if we confess our sins, he will forgive our sins, because we can trust God to do what is right. He will cleanse us from all the wrongs we have done. If we say we have not sinned, we make God a liar, and we do not accept God's teaching.
(c) Holy Bible, New Century Version, 2005
The word "light" here is used as a symbol of God's goodness or truth. Darkness would be the opposite - i.e. Satan's evilness and lies. Living in the light allows us to fellowship with God Himself. To me, this is mind-blowing. There is something I can do that puts me in fellowship with the One who created everything. He is so far beyond anything I can comprehend, and yet He says he'll fellowship with me.
I encourage you - live in the light. He gives us grace to do so - you don't have to do it in your own strength. Trust Him, pray to Him, live according to His word. It's worth it.