Matthew 5:14-16  " You are the light of the world."  Kingdom citizens are "phos" - to shine; to manifest; rays of luminousness..  

As rays of light, Jesus teaches, we "cannot be hidden".. and we should not try to hide ourselves.  Instead we need to shine.. to "give light to all who are in the house."  We are to shine "before men is such a way that they may see [our] good works, and glorify [our] Father who is in heaven," 

Jesus said, "I am the light of the world; he who follows Me shall not walk in darkness, but shall have the light of life." ( John 8:12)  In John 9:5 He said, "While I am in the world, I am the light of the world." Later, He said, "For a little while longer the light is among you. Walk while you have the light, that darkness may not overtake you; he who walks in darkness does not know where he goes. While you have the light, believe in the light, in order that you may become sons of light." ( John 12:35-36) And in verse 46 He added, "I have come as light into the world that everyone who believes in Me may not remain in darkness." 

Light.. created by God on that first day.. "Let there be light" He spoke, "and there was light. And God saw that the light was good; and God separated the light from the darkness."  The Hebrew word for separated means to divide or distinguish, to differ, or select.   Jesus tells us that His disciples are to be separated from darkness.. that there is a distinction between believers and unbelievers that is as different as light is from darkness.. as day is from night. 

In John 3:19-21 Jesus said, "And this is judgement, that the light is come into the world, and men loved the darkness rather than the light; for their deeds were evil. For everyone who does evil hates the light, and does not come to the light, lest his deeds should be exposed. But he who practices truth comes to the light, that his deeds may be manifested as having been wrought in God." 

John continues this theme in his letters.. "And 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. If we say that we have fellowship with Him and yet walk in darkness, we lie and do not practice the truth; 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 sins." ( I John 1:5-7)

So, to be light.. we must be separate, distinguished from darkness. We must be walking in and practicing truth. We must do the works of God for His glory. We must not hide that light that is in us.. Jesus, the Light of the world. 

Father in heaven, You are Light and in You there is no darkness!  Hallelujah! We believe in Jesus Christ, the Light of the world and we walk in that truth, to honor and glorify You.  Let Your Light shine in us and through us, Lord God. May we never hide the Light that You have lit in our hearts, putting away every evil practice, confessing every sin, and finding life in the Light of Jesus Christ our Savior.  Come Spirit of God and shine in our hearts today, for the glory of the Father and of the Son. Amen.