. . . (Jesus is) The true Light, which lighteth every man that cometh into the world. He was in the world, and the world was made by him, and the world knew him not. He came unto his own, and his own received him not. But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
John 1:9-13 KJV

“Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” 
John 3:3b ESV

(God) called [us] out of darkness into his marvelous light.                    
1 Peter 2:9b ESV

“You are the salt of the earth. But what good is salt if it has lost its flavor? Can you make it salty again? It will be thrown out and trampled underfoot as worthless. You are the light of the world—like a city on a hilltop that cannot be hidden.                
Matthew 5:13-14 NLT

So from now on we regard no one from a worldly point of view. Though we once regarded Christ in this way, we do so no longer… We are therefore Christ’s ambassadors, as though God were making his appeal through us. We implore you on Christ’s behalf: Be reconciled to God. God made him who had no sin to be sin for us, so that in him we might become the righteousness of God.  
2 Corinthians 5:16,20-21 NIV

"As the Father has sent me, I am sending you." And with that he breathed on them and said, 'Receive the Holy Spirit.’
John 20:21b–22  NIV