Jesus said, “You are the light of the world” (Matt. 5:14). We believers are to be lights that shine in the world and dispel the darkness. However, like most of the things that are stated in the Bible, we understand them much better if we understand them in the context of the whole scope of Scripture. Believers are lights, but it helps us keep that in proper perspective when we realize that our light is derivative—we get it from God. We do not originate the light, we reflect the light.
Jesus, too, recognized that he was “the light” or “a light” only by virtue of the fact that he reflected the light of God. We commonly hear that Jesus said “I am the light of the world,” but good translations of the New Testament show us that of the three times that Jesus referred to himself as light, only once did he say that he was “the” light, the other two times he referred to himself as “a” light.
(YLT) when I am in the world, I am a light of the world.’
(YLT) I a light to the world have come, that every one who is believing in me–in the darkness may not remain;
In the two verses above Jesus referred to himself as “a” light. He knew that other people who reflected the light of God into the world were also lights. There is one time in Scripture when Jesus referred to himself as “the” light, and when we read what he said in its context, we understand why he did that.
When Jesus spoke again to the people, he said, “I am the light of the world.
Jesus made this statement while speaking at the Feast of Tabernacles (also sometimes called “the Feast of Booths,” John 7:2), which is one of the three feasts that the Law of Moses said the Jews were to attend each year.  The Feast of Passover occurred in the spring, the Feast of Pentecost occurred in the summer, and the Feast of Tabernacles occurred in the fall, usually our September. The way it was celebrated at the Time of Christ, the Feast of Tabernacles was an eight day feast, and the Feast of Tabernacles that is recorded in John 7 and 8 was the last of the three major feasts that Jesus attended before he was killed at the Passover Feast the next year.
When we read the record in John chapters 7 and 8 we can see that Jesus was trying to reveal to people that he was the Messiah, but was doing so in a way that those with an open heart would understand, while those with cold hearts would not. Jesus’ words and actions did indeed convince people, because day after day as the Feast progressed, more and more people believed in him. John 7:31 says “many in the crowd put their faith in him.” Then, John 7:41 says people declared, “He is the Christ.” Still later, on the last day of the feast, John 8:30 says, “Even as he spoke, many put their faith in him.” Thus, in the context of revealing that he was the Messiah, it makes sense that he would say he was “the” light of the world. He was not being exclusive and claiming to be the only light, he was claiming to be the major light, the promised Messiah.
The fact that Jesus said to the people, “you are the light of the world,” (Matt. 5:14) shows us that he did not think of himself as the only light. We all have the privilege and responsibility to reflect God’s light. In contrast to people and even the Messiah, who all reflect the light of God, God Himself is not “a” light, or even “the” light, God is “light” (1 John 1:5). In God is no darkness at all. He shines brilliantly and has done so forever. Isaiah said God would be people’s everlasting light.
The sun will no more be your light by day, nor will the brightness of the moon shine on you, for the LORD will be your everlasting light, and your God will be your glory.
There is a day coming in the future when the city of God will descend from heaven (Rev. 21:2), and every saved person will be in it with God forever. In a way we just cannot understand at this time, but the Bible foretells, the city will be illuminated directly by the light of God, apart from the light sources we are used to today such as the sun and moon. At that time, darkness of every kind will cease to exist, and there will be no such thing as “night.”
There will be no more night. They will not need the light of a lamp or the light of the sun, for the Lord God will give them light. And they will reign for ever and ever.
In contrast to the future, today the light that constantly radiates from God is reflected by believers and seen by others, which is why Jesus said, “You are the light of the world.” 2 Corinthians 3:18 speaks of us reflecting the light of God which we see in the person of Jesus Christ. Before we go into that, however, it is important to discuss the verse itself and see what it is saying. Reading the two versions below shows that there is disagreement among the scholars as to whether we are “beholding as in a mirror” (i.e., “looking at as in a mirror”) the glory of the Lord (NASB), or are “reflecting” the glory of the Lord (NIV).
2 Corinthians 3:18 (NASB)
But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as from the Lord, the Spirit.
2 Corinthians 3:18 (NIV)
And we, who with unveiled faces all reflect the Lord’s glory, are being transformed into his likeness with ever-increasing glory, which comes from the Lord, who is the Spirit.
The disagreement between the two verses above is due to the fact that the Greek verb the NASB translates “beholding as in a mirror,” and the NIV translates “reflect,” is katoptrizomai (#2734 katoptri,zomai). Checking different lexicons shows that katoptrizomai can mean “to see one’s self in a mirror,” and it can also mean “to reflect, as a mirror does.” The scholars and translators, and thus the versions, are divided as to which meaning is the primary one in 2 Corinthians 3:18. Leaning toward “beholding as in a mirror” the glory of the Lord are versions such as the ASV, ESV, KJV, NAB, and NASB. Leaning toward “reflecting” the glory of the Lord are versions such as the HCSB, NET, NIV, NJB, and NRSV.
When a Greek word has two meanings, it can be very difficult to choose the “right” one for the verse. We must also remember that “all Scripture is God-breathed” (2 Tim. 3:16), and as the vocabulary of God, it is certain that He could have picked a different word than He did for this verse. We know He did not choose a word with two meanings just so Christians could fight about it. Either He thought that the context would clearly lead us to the correct meaning of the word, or He felt that both meanings were important, even if one was more dominant than the other. That certainly seems to be the case here.
To fully understand what 2 Corinthians 3:18 is saying and to be able to translate and interpret it correctly, we must understand the record in Exodus 34, which is about Moses’ face radiating the glory of God.
(29) When Moses came down from Mount Sinai with the two tablets of the Testimony in his hands, he was not aware that his face was radiant because he had spoken with the LORD.
(30) When Aaron and all the Israelites saw Moses, his face was radiant, and they were afraid to come near him.
(31) But Moses called to them; so Aaron and all the leaders of the community came back to him, and he spoke to them.
(32) Afterward all the Israelites came near him, and he gave them all the commands the LORD had given him on Mount Sinai.
(33) When Moses finished speaking to them, he put a veil over his face.
(34) But whenever he entered the LORD’s presence to speak with him, he removed the veil until he came out. And when he came out and told the Israelites what he had been commanded,
(35) they saw that his face was radiant. Then Moses would put the veil back over his face until he went in to speak with the LORD.
The record of Exodus 34:29-35 and Moses’ face radiating occurred on Moses’ seventh time coming down Mount Sinai from being with God, and was the second time God had written the Ten Commandments on stone tablets. Exodus 34:29 tells us that Moses’ face was radiant. The Hebrew text says that Moses’ face shined. Moses’ face was reflecting the brilliant light of God, and it was shining so brightly that the Israelites, including Aaron the High Priest, were afraid of him (34:30), and he had to cover his face with a veil (34:33, 35). The illustration of Moses’ face shining forth the light of God is developed in 2 Corinthian 3:7-16, which gives us many details about it.
When it comes to making a choice as to whether katoptrizomai means “beholding as in a mirror” or “reflecting,” it seems natural that 2 Corinthians 3:18 would follow the example of Moses that is being given in the chapter. This means it would refer to our “reflecting” the glory of the Lord for others to see just as Moses radiated the glory of God for the Israelites to see. It is not clear how “looking at oneself in a mirror” is relevant to Moses or to us. Moses certainly did not see himself in any kind of mirror, he looked at God. Similarly, we do not have any glory on our own, so there does not seem to be any reason to look at ourselves in a mirror. The only reason that “beholding as in a mirror” would fit this verse in any meaningful way is that no one can reflect something he is not looking at first. A mirror cannot reflect sunlight into a dark room unless it is pointed at the sun; “looking at” the sun, if you will. When a mirror “looks at” the sun, the light is reflected off of it out to others. Similarly, we will never reflect the glory of the Lord unless we look at it. So there is a sense in which “looking at” is a sub-theme of 2 Corinthians 3:18.
Having pointed out that Moses’ face shone so brightly with the glory of the Lord that the people were afraid, we must also notice that Exodus 34:29 says that Moses’ face shined “because he had spoken with the LORD.” Thus it is part of the record in Exodus that the only reason Moses could radiate the glory of the LORD to others was because he had seen it himself, and thus it makes sense that the Greek text of 2 Corinthians 3:18 would contain the subtheme of looking at the glory of the Lord as well as the theme of reflecting the glory of the Lord.
Once we understand that the concept of reflecting the glory of the Lord in 2 Corinthians 3:18 comes from the example of Moses recorded in Exodus 34, we need to pay attention to the differences and similarities between Exodus and 2 Corinthians. There are distinct differences between the record in Exodus and the record in Corinthians, and God is teaching us wonderful lessons in both places.
One of the major differences between the record in Exodus and 2 Corinthians is that in Exodus, Moses spoke directly with God and the people saw the glory reflected on Moses’ face, but Moses was a fallen human and the glory that he radiated was not permanent; it faded away (2 Cor. 3:7, 11, and 13). We all understand that because at one time or another each of us has been profoundly affected by something, and perhaps even said, “I will never forget that,” or felt like the emotion of the moment would never leave; but we do forget and emotions pass. The Israelites only saw the glory on Moses’ face for a little while, and then it was gone. Moses could not hold it forever. Today, however, the glory of God is not found on Moses’ face, but in Jesus Christ and on his face (2 Cor. 3:14, 16, 18, and 4:6), and that glory is permanent (2 Cor. 3:11). We can always see the glory on the face of Jesus, and can always be lightened, empowered, and transformed by it.
A similarity between Exodus and Corinthians is that in Exodus the glory of God shone from Moses’ face, while today the glory is spoken of as being in the Lord, and specifically on his face. This is why 2 Corinthians speaks of “the glory of God in the face of Jesus Christ.”
2 Corinthians 4:6
For God, who said, “Let light shine out of darkness,” made his light shine in our hearts to give us the light of the knowledge of the glory of God in the face of Christ.
This verse needs to be understood in light of its context, which is chapter 3. There are times when the chapter divisions that have been added to the Bible do not help people understand it. Most people just assume that new chapters start new subjects, and chapter 4 is a new subject from chapter 3. In this case, however, the glory of God was on the face of Moses in chapter 3, and it is on the face of Jesus in chapter 4. The glory faded from Moses’ face, but will never fade from Jesus’ face.
There is a biblical custom about the “face” that is helpful to understand. In the biblical culture, the word “face” indicated an intimacy and a connection. The glory that was on Moses’ face was a physical reality, surely, but it is meaningful that Moses’ whole body did not shine. When it comes to Jesus, however, the Word of God says that the glory of God is in the “face” of Jesus, which is more than a physical reality, it is a spiritual lesson. To get “face to face” with Jesus takes more than just “head knowledge.” It takes “fellowship,” full sharing. We must fully give ourselves to him, just as he has done and is doing for us.
That brings us to a final point and another profound difference between the records in Exodus and Corinthians: being face to face with Jesus and seeing and reflecting his glory actually transforms us. There is no indication that Moses or the people who looked at the glory reflected in his face became personally transformed. Yet that is exactly what the Bible says about us who reflect the Lord’s glory—we are transformed into Christ’s likeness, Christ’s appearance.
2 Corinthians 3:18
And we, who with unveiled faces all reflect the Lord’s glory, are being transformed into his likeness with ever-increasing glory, which comes from the Lord, who is the Spirit.
The light of God radiating from Jesus Christ, which we experience as we fellowship with him minute by minute in our hearts and minds, actually transforms us into his “likeness,” or “image.” We can better understand what this means by examining the Greek text. The Greek word for “likeness” or “image” is eik?n (Strong’s #1504 ?????,), which has different meanings in different contexts, but here means, “form” or “appearance.” We have all seen Christians who the Bible would refer to as “carnal” Christians. They focus their lives on worldly things and do not have much time for God, and their lives (and usually their faces) show it. They do not reflect the glory of God and are not transformed into Christ’s glowing appearance. It is God’s desire for us that we are all “face to face” with Jesus, in full fellowship with him, giving our lives to him, and reflecting his glory for all the world to see. That kind of intimate participation in the things of Christ is a choice, and we all make it.
When it comes to reflecting the light of God as we look on the face of Jesus Christ, God created a wonderful object lesson for us: the moon. God often teaches us through nature, which is why he tells us to “go to the ant” (Prov. 6:6), or why He used the ox and donkey to reprove Israel (Isa. 1:3). The moon rules the night sky, and when there is a full moon it shines so brilliantly white that it is easy to see outside. In fact, the full moon is so bright that objects cast a distinct shadow in its light. However, that is not the case if there is a lunar eclipse. A lunar eclipse occurs when the earth gets between the sun and moon. In those times the moon is a full moon, but it looks very different from the normal monthly full moon. We can still usually see it, but with some difficulty. It is dark and has red overtones. It seems ominous and gloomy. What is the difference between the brilliantly white full moon and the dark and gloomy moon of the lunar eclipse? The brilliantly lit full moon is “looking at” the sun and reflecting its light. In sharp contrast, the full moon in eclipse is “looking at” the earth, and it seems to reflect all the darkness, anger, and gloom of the earth.
The difference between a regular full moon and the full moon of a lunar eclipse is a wonderful lesson. Just like the moon, if we look at the sun (oops, Son), and focus our gaze on him, we will reflect his light. We will shine brightly, and the light we reflect will be a blessing to ourselves and to others. If, on the other hand, we look at the earth and focus our lives on earthly things, we will be just like the moon—our lives will be dark and ominous, angry and depressed.
We each have the opportunity to be “transformed into his likeness with ever-increasing glory.” Day after day as we fellowship with, and focus on, the things of God, we will shine brighter and brighter, and there will indeed be “ever-increasing glory.” At the end of each day every one of us can think back over the day and see whether we have decided to fellowship with Christ and give ourselves to him or not. If we do, we will shine brighter and brighter. The world is a dark place and people need the light of Christ that we can shine into their lives. If we will focus on Christ we can be that light.
Exodus 23:14-17 (ESV).
 All seven times that Moses ascended and descended Mount Sinai are in Exodus. First time: 19:3 up; 19:7 down. Second time: 19:8 up; 19:14 down. Third time: 19:20 up; 19:25 down. Fourth time: 20:21 up; 24:3 down. Between the fourth and fifth time up Moses went part way up with the elders of Israel: 24:9. Fifth time: 24:15 up (he was there 40 days and 40 nights (24:18) and got the Ten Commandments on stone (32:15) during this fifth trip; 32:15 down. Sixth time: 32:31 up; 32:35 he is commanded to go down. Seventh time: 34:4 up; 34:29 down.
 The first set of stone tablets God Himself carved out of stone and wrote on (31:18; 32:15, 16). After Moses broke them, God told Moses to chisel out two new tablets (no easy task with bronze tools) and He (God) would write on them (34:1, 29).
 The Hebrew word is qaran (Strong’s #7160) and means “to shine.”
 A major reason that some scholars chose “beholding” is that they believe the verb is in the middle voice. However, katoptrizomai in this verse can be passive or middle voice, and the middle voice can act like an active voice, in this case, “to reflect.” For a helpful treatment of the subject see, Simon Kistemaker, New Testament Commentary: 2 Corinthians (Grand Rapids, MI, Baker Academic, 1997), p. 128.
 Arndt, William F., and Gingrich, F. Wilbur, A Greek English Lexicon of the New Testament and Other Early Christian Literature, (Chicago, The University of Chicago Press, 1979), p. 222.
 A “new moon” occurs when the moon is between the earth and sun, and during these times the moon is invisible, being completely overpowered by the sun’s light. In contrast, a “lunar eclipse” is when the earth comes between the sun and moon, and the shadow of the earth darkens the moon. Unlike the “new moon,” which occurs every month, lunar eclipses do not occur regularly. In a lunar eclipse the moon is visible only because light from the sun is refracted (bent) by the earth’s atmosphere and shines a little bit on the moon. During a lunar eclipse the moon takes on a red tint because the sunlight has gone through the dense layer of the earth’s atmosphere and this causes the longer wavelengths of light (the red) to be most prevalent. It is the same reason sunrises and sunsets are dominated by red colors and the sun often looks like a red ball, while when the sun is straight overhead it seems more yellow or yellow-white. The intensity of the red tint on the moon varies from one lunar eclipse to another because when there is more dust (and sometimes clouds) in the atmosphere the red wavelengths dominate even more than when the atmosphere is clearer.