God is light, and in Him is no darkness at all. If we claim to be His, we need to be reflecting that same light.
1 John 1:5-10
5 This is the message we have heard from Him and announce to you, that God is Light, and in Him there is no darkness at all.
6 If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth;
7 but if we walk in the Light as He Himself is in the Light, we have fellowship with one another, and the blood of Jesus His Son cleanses us from all sin.
8 If we say that we have no sin, we are deceiving ourselves and the truth is not in us.
9 If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.
10 If we say that we have not sinned, we make Him a liar and His word is not in us.