"No one after lighting a lamp puts it in a cellar or under a basket, but on a stand, so that those who enter may see the light. Your eye is the lamp of your body. When your eye is healthy, your whole body is full of light, but when it is bad, your whole body is full of darkness. Therefore be careful lest the light in you be darkness. If then your whole body is full of light, having no part dark, it will be wholly bright, as when a lamp with it's rays gives you light."
This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all. If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth. 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 cleanses us from all sin. If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say we have not sinned, we make him a liar, and his word is not in us.
(1 John 1:5-10)
For God, who said, “Let light shine out of darkness,” has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.
2 Corinthians 4:6