Jesus said we are the light of the world, and we’re commanded to walk in the light, so what does it mean and how can we do it?
In the Beginning
The Bible isn’t really a book about the creation of the heavens as much as it’s a book about how to get to heaven, but Genesis 1:1 isn’t the actual beginning. Genesis 1:1 says “In the beginning, God created the heavens and the earth,” but if you read John 1, you’ll see we can go back before the creation. The Apostle John writes, “In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God” (John 1:1-2), so there is no mention of the creation yet, until John writes, “All things were made through him, and without him was not any thing made that was made” (John 1:3), so Jesus, as the Word, and as God, was with God, or with the Father before creation. Obviously Jesus existed before creation, time, matter, and before us! He is without beginning and without end (Heb 7:3), and only after He created the universe was there light to be seen by mankind. So, “In him was life, and the life was the light of men. The light shines in the darkness, and the darkness has not overcome it” (John 1:4-5). Darkness cannot overcome the light, but the light always overcomes darkness, so Jesus, as the Light of the World, has overcome the darkness of this world, and has brought light to those who later put their trust in Him. He makes us the lights of the world, but like the moon, we have no source of light. Just as the moon must reflect the light of the sun to be seen, so we should reflect the Son of God to be seen by others.
Light of the World
Most of us don’t even realize that we’re walking in darkness until the Light of the World exposed the darkness for us. Jesus said, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life” (John 8:12), so if you are following Jesus, you’re not going to walk in darkness, and stumble over things in the dark, but rather, as He is the Light, we should be in the light. If we continue to follow Him, we won’t get off the path and into the darkness again. The Apostle John wrote, “The true light, which gives light to everyone, was coming into the world. He was in the world, and the world was made through him, yet the world did not know him” (John 1:9-10), so even though He is their Creator, yet the world doesn’t know Him. If they don’t know Him, then the light that we bring into the world might hurt their eyes at first. We are the light of the world, but that doesn’t mean we shine it directly in their face. It hurts when someone shines a flashlight in my eyes, so being a flashlight in the darkness is fine, but just not in the face! It’s far too easy to say you’re being persecuted for your faith when it’s really just being obnoxious and trying to shove Christ down people’s throat. The Apostle Paul, in speaking of the lost who are still living in darkness, wrote that “the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God” (2 Cor 4:4). It is not us, but “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 Cor 4:6). We can’t make them see the light just as you can’t make a blind man see! God may use us as a means to point them to the Light, but truly, only God’s Spirit can reveal Who the Light of the World is (Prov 21:1; John 6:44). We can however, remind them where the light switch is at (Rom 10:9-13).
Walking in the Light
Jesus taught His disciples, “You are the light of the world. A city set on a hill cannot be hidden. Nor do people light a lamp and put it under a basket, but on a stand, and it gives light to all in the house. In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven” (Matt 14-16), so walking in the light is allowing God’s light to shine through us, and why? It is “so that they may see your good works,” but not so they’ll give us a pat on the back, but they’ll “give glory to your Father who is in heaven.” The light we walk in is for others to see….and hopefully, through us, they will see Christ. We are not that light; Jesus is, but to walk in the light, we must first acknowledge that we were once in darkness. The Apostle Paul writes, that, “at one time you were darkness, but now you are light in the Lord. Walk as children of light” (Eph 5:8), but it was God Who brought to “light for everyone what is the plan of the mystery hidden for ages in God, who created all things to bring to light for everyone what is the plan of the mystery hidden for ages in God, who created all things” (Eph 3:9). Sadly, we’ve got to use caution and have good discernment to avoid what looks like light, but may actually be artificial light, because “even Satan disguises himself as an angel of light” (2 Cor 11:14). Not everything that glitters is gold, and in fact, it may turn out to be “fool’s gold.” Walking in the light means living out the words Jesus taught. The Apostle John said we can’t be in the darkness and in the light at the same time, writing, “Whoever says he is in the light and hates his brother is still in darkness” (1 John 2:9), but “Whoever loves his brother abides in the light, and in him there is no cause for stumbling” (1 John 2:10).
Walking in the light means you are following Christ so closely, that it’s almost like being in the presence of Christ Himself. Your behavior is reflective of the Son of God, Jesus Christ, Who taught, “Love your enemies, do good to those who hate you, bless those who curse you, pray for those who abuse you” (Luke 6:27-28), and this will show that “you will be sons of the Most High, for he is kind to the ungrateful and the evil” (Luke 6:35). That gives us reason to “Be merciful, even as your Father is merciful” (Luke 6:36), since it was “while we were still weak, at the right time Christ died for the ungodly” (Rom 5:6), so “God shows his love for us in that while we were still sinners, Christ died for us” (Rom 5:8), and amazingly, “while we were enemies we were reconciled to God by the death of his Son” (Rom 5:10a). That kind of sacrificial love should be what we are following, and will be, if we are following in Christ, and if we are following Christ, we’ll be walking in the light.
Here is some related reading for you: 7 Great Bible Verses About Walking in the Light 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible : English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.