In Jesus’ Sermon on the Mount in Matthew 5-7. He describes those in the Kingdom of Heaven as being blessed when they are:
Matthew 5:3-11 NKJV “Blessed are the poor in spirit, For theirs is the kingdom of heaven. Blessed are those who mourn, For they shall be comforted. Blessed are the meek, For they shall inherit the earth. Blessed are those who hunger and thirst for righteousness, For they shall be filled. Blessed are the merciful, For they shall obtain mercy. Blessed are the pure in heart, For they shall see God. Blessed are the peacemakers, For they shall be called sons of God. Blessed are those who are persecuted for righteousness’ sake, For theirs is the kingdom of heaven. “Blessed are you when they revile and persecute you, and say all kinds of evil against you falsely for My sake. (emphasis mine)
As citizens of the Kingdom of heaven they have a personal relationship with Jesus Christ the King and ruler over the Kingdom.
John 1:10-13 NKJV He was in the world, and the world was made through Him, and the world did not know Him. He came to His own, and His own did not receive Him. But as many as received Him, to them He gave the right to become children of God, to those who believe in His name: who were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God. (emphasis mine)
The people with a personal relationship with the King have tremendous influence and as such should use that influence for the kingdom; to advance it by increasing its population and making sure that it runs or operates under the way the King designed it.
2 Timothy 3:16-17 CEV Everything in the Scriptures is God's Word. All of it is useful for teaching and helping people and for correcting them and showing them how to live. The Scriptures train God's servants to do all kinds of good deeds.
As a person with influence Jesus described you as light:
Matthew 5:14-16 NKJV “You are the light of the world. A city that is set on a hill cannot be hidden. Nor do they light a lamp and put it under a basket, but on a lampstand, and it gives light to all who are in the house. Let your light so shine before men, that they may see your good works and glorify your Father in heaven. (emphasis mine)
The "you" is emphatic in the Greek text, so that we might translate it "You, and you alone are the light of the world.".
Light has several functions.
(1) Light dispels darkness. Our lives should have such an influence that wherever we are, we dispel darkness.
Matthew 4:12-16 CEV When Jesus heard that John had been put in prison, he went to Galilee. But instead of staying in Nazareth, Jesus moved to Capernaum. This town was beside Lake Galilee in the territory of Zebulun and Naphtali. So God's promise came true, just as the prophet Isaiah had said, “Listen, lands of Zebulun and Naphtali, lands along the road to the sea and across the Jordan. Listen Galilee, land of the Gentiles! Although your people live in darkness, they will see a bright light. Although they live in the shadow of death, a light will shine on them.”
(2) Light reveals. The light of Jesus Christ reveals the darkness that is in others.
John 3:17-18 CEV God did not send his Son into the world to condemn its people. He sent him to save them! No one who has faith in God's Son will be condemned. But everyone who doesn't have faith in him has already been condemned for not having faith in God's only Son.
(3) Light shows the way out of darkness. We should be leading men out of darkness through that work of God's love and Spirit in our lives.
1 John 1:6-7 CEV If we say we share in life with God and keep on living in the dark, we are lying and are not living by the truth. But if we live in the light, as God does, we share in life with each other. And the blood of his Son Jesus washes all our sins away.
1. Bear Witness
John 1:6-9 NKJV There was a man sent from God, whose name was John. This man came for a witness, to bear witness of the Light, that all through him might believe. He was not that Light, but was sent to bear witness of that Light. That was the true Light which gives light to every man coming into the world.
The role of a witness is to answer questions truthfully and give an honest account of what they have seen and heard. As Christians, we can be light in the darkness by responding to non-believers with truth and testifying to what God has done. Remember, it is not our job to make people believe, but to share the truth boldly and lovingly.
John bore witness to Jesus because he knew without a doubt Who Jesus was and what He would do for the world.
John 1:29-30 NKJV The next day John saw Jesus coming toward him, and said, “Behold! The Lamb of God who takes away the sin of the world! This is He of whom I said, ‘After me comes a Man who is preferred before me, for He was before me.’
2. Follow Jesus' Commands
John 8:12 NKJV Then Jesus spoke to them again, saying, “I am the light of the world. He who follows Me shall not walk in darkness, but have the light of life.”
When you choose to follow the commands of the Lord and reject the ways of the world, others will notice. Especially when you hold fast to what is true, your light will shine. Though people may reject it, there will be some who are drawn in, curious as to why you live differently.
The challenge for us is to keep our eyes on the One we follow. For the moment we take our eyes off of the Savior, we will be tempted to slip into the darkness of the world. Just as Jesus set his face like flint toward the redeeming cross, we too must set our faces like flint toward the Redeemer.
The Bible says that if we claim to be in communion with the Lord, but walk in darkness, we are not practicing the truth.
I John 1:5-7 NKJV This is the message which we have heard from Him and declare to you, that God is light and in Him is no darkness at all. If we say that we have fellowship with Him, and 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 Christ His Son cleanses us from all sin.
3. Put Yourself Out There
It can be a little scary thinking about shining the light of Jesus for all to see. It’s much safer to casually mention Him, in hopes of not offending anyone. However, Jesus proclaimed that His disciples were the light of the world. They were not to remain hidden. They were called to shine their light as a city set on a hill.
We are Jesus’ disciples too. We’re not meant to stay tucked away in our protected corner of the world. We are to boldly let our light shine before men!