What is light? That is a good question - light has properties of both a wave and a particle. This was an astounding discovery and is certainly outside the realm of how we normally perceive things. Billiard balls act as particles, while oceans act as waves. Photons act as both a wave and a particle all the time (even though it's common, but basically incorrect, to say that it's "sometimes a wave and sometimes a particle" depending upon which features are more obvious at a given time).
Electromagnetic radiation travels in waves but unlike ocean waves, light travels through empty space and even though it weighs nothing it carries with it energy that can do work. The different types of electromagnetic radiation are determined by wavelength, which also corresponds to energy. Radio waves have long wavelengths, measured in meters, and have relatively low energy. Light waves have short wavelengths, measured in hundreds of nanometers (a nanometer billionth of a meter) on the order of the size of molecules and much higher relative energy (this is how light reacts chemically with the cone receptors in your retina.) X-rays have energy that allows them to pass through most physical things without much interactions (leaving only a shadow on an x-ray film) and gamma rays from cosmic events have wavelengths that make the nucleus of an atom look like a solar system.
For comparison, if the shortest wavelength in our world was a meter, the longest wavelength would be about 10 times farther than the sun is from the earth.
What we sense what we need to interact with the physical world – a 0.3 mm diameter very thin spot on our retina (just larger than the diameter of a human hair) contains six to seven million cone cells sense but a that see only a tiny fraction of the wavelength of light in the universe - a matter of a few millimeters on that line that extends 10x past the sun.
Light tends to interact with things that are proportional in size to the wavelength. A big and heavy ship on the sea won't sense little waves, just bigger and longer ones of similar size. How does light interact? Light is more often absorbed and re-radiated than transmitted. Where does it come from?
The first creative act of God recorded in Genesis chapter 1 is the creation of light:
And the earth was formless and void, and darkness was over the surface of the deep; and the Spirit of God was moving over the surface of the waters. Then God said, “Let there be light”; and there was light. And God saw that the light was good; and God separated the light from the darkness (Genesis 1:2-4). At the beginning of this creation account, the earth was dark and in disarray (formless and void). At the end, it has light and is ordered. The progress is from darkness to light and for disorder to order. Light was created by God to separate darkness and light. Paul will later draw on this creation of light and relate it to godly living (see 2 Corinthians 4:3-6).
Light can organize molecules in nature and cause them to interact with other molecules – be the source of energy that causes them to bind and form something larger. Light can be used in medicine to promote healing and to selectively destroy certain things without harming others nearby. Light can be a penetrating organizing energy or something that destroys.
In Genesis we find: "1 In the beginning God created the heavens and the earth. 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters. 3 And God said, “Let there be light,” and there was light. 4 God saw that the light was good, and he separated the light from the darkness. 1 John 1:5 says that God is light and in Him is no darkness at all. This is the God who said, “Out of darkness light shall shine…” and the same God, “…who shined in our hearts to illuminate the knowledge of the glory of God (2 Cor. 4:6).”
As it says in our scripture on the bulletin board as you entered the center "- that you may declare the praises of him who called you out of darkness into his wonderful light. 1Peter2:9
If we are honest, we must admit that we were just like the people in Matthew 4:16 who were, “…sitting in darkness…” and in, “…the region of the shadow of death.” But, “…because of the merciful compassions of our God, in which the rising sun visited us from on high (Lk. 1:78)” we have, “…seen a great light…” and to us, “…light has risen (Matt. 4:16).” This light is none other than God Himself.
When the Lord Jesus came, He introduced Himself in John 8:12 as, “…the light of the world.” He did this so that, “…everyone who believes into [Him] would not remain in darkness (John 12:46)” or, “…walk in darkness.” Rather, “…he who follows [Him] shall have the light of life (John 8:12).”
Unfortunately, "…humans love the darkness rather than the light, and our works show it.
"For every one who practices evil hates the light, and does not come to the light, lest his works be reproved" (John 3:20). But, "…he who does the truth comes to the light, that his works may be manifested that they are wrought in God" (John 3:21). So, how can we be those who do the truth and come to the light?
There’s a story about a woman who was lost a ring as she was crossing the street to get to her car. She decided to look for it. Having no light of her own she walked over to the nearby streetlamp and started looking there. Several people offered to help. When one asked her why she was looking below the lamp post when her car was parked a-ways away, she replied – “the is where the light is.“ Without the light, we can be lost. Without the light, we can’t even know where to start. This is why the light of Christ in us is so very important!
And we are surrounded by people who love darkness rather than the light. Sure, we are Christians and have the light of life in us, but it is still possible to be affected by those around us who are walking in darkness. It’s easy to bump into things on the edge of the light because they don’t reflect the light. We can get tangled up in things that don’t reflect the light. Dark things don’t reflect the light… We may have had a good start in our Christian life, yet gradually be lulled to sleep and begin to fall into a walk that is just like that of the people around us. We can be affected by dark things we take in from the news or certain types of entertainment like movies, music, and books.
We need to consider 1 Thessalonians 5:4-6:
4 "But you, brothers, are not in darkness that the day should overtake you like a thief;
5 For you are all children of light and children of the day. We are not of the night nor of darkness.
6 So then let us not sleep, as the rest do, but let us watch and be sober."
Also, 1 John 1:6-7 helps us with this: "6 If we say that we have fellowship with Him and yet walk in the darkness, we lie and are not practicing the truth; 7 But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus His Son cleanses us from every sin."
To be a Christian today is not easy. We live in a world full of darkness, but we’ve been called out of darkness into His marvelous light: "But you are a chosen race, a royal priesthood, a holy nation, a people acquired for a possession, so that you may tell out the virtues of Him who has called you out of darkness into His marvelous light." 1 Peter 2:9
As it says in Colossians 13 "For He delivered us from the domain of darkness, and transferred us to the kingdom of His beloved Son, 14 in whom we have redemption, the forgiveness of sins"
This change in our condition should be accompanied by a corresponding change in our conduct. At the beginning of chapter 4, Paul exhorts each believer to walk in a way that is consistent with his calling as a Christian: “I, Therefore, the prisoner of the Lord, entreat you to walk in a manner worthy of the calling with which you have been called” (Ephesians 4:1). The Christian “walk” or Christian lifestyle has been described in several different ways thus far in Ephesians 4 and 5. The Christian is to walk in unity and in community with his fellow saints (4:1-16).102 The Christian is to walk in a way that is dramatically different from his walk as an unbeliever (4:17-32). Christians are further instructed to “walk in love” (5:1-6). And now, Paul speaks of the Christian’s lifestyle as a “walk as children of light” (5:7-14). If we are to walk in a manner that is consistent with our calling, Paul instructs us, we are to live as those who are “children of light.”
It may be good to pause for a moment, and to reflect on what Paul is telling us, for Paul’s teaching and the popular perception of Christianity differ greatly. The gospel is often presented as though faith in Jesus Christ requires no great change, and that one need but to “add” Christ to his experience, to “invite Christ into his life,” and then life will become more pleasant, but at little cost to the Christian. Jesus spoke of discipleship, and he cautioned those who would too quickly follow Him to “count the cost” (see Luke 9:23-24, 57-62; 14:25-25).
Becoming a Christian is not so much a matter of adding Christ to your life as it is abandoning your life to find true life in Christ. And when one thus trusts in the person and work of Jesus Christ, the change is not small. It is a radical transformation. It is a change from death to life, from darkness to light. Paul’s words indicate that our calling as Christians should have a radical impact on our conduct. We will never be the same again. We should never think or act the same. Our thinking and our behavior after our conversion should compare to our former “walk” as though it were night and day.
The night is far advanced. We need to continually encourage one another!"The night is far advanced, and the day has drawn near. Let us therefore cast off the works of darkness, and let us put on the weapons of light." Rom. 13:12
Romans 14:19 "Let us therefore follow after the things which make for peace..."
Ephesians 4:29 "Let no unwholesome talk come out of your mouths, but only what is helpful for building up the one in need and bringing grace to those who listen."
Jude 1:20, "But you, beloved, by building yourselves up in your most holy faith and praying in the Holy Spirit..."
1 Thessalonians 5:11, "Therefore encourage one another and build each other up, just as in fact you are doing."
What are the weapons of light? Ephesians 6:11-18 tells us to,
11 Put on the whole armor of God that you may be able to stand against the stratagems of the devil.
12 For our wrestling is not against flesh and blood but against…the world rulers of this darkness…
In John 9:5, the Lord said, “While I am in the world, I am the light of the world.” It’s very interesting that He added the qualifying phrase, “While I am in the world.” Did that mean that once He left the world He would no longer be the light of the world? Or that there would cease to be light in the world?
Three chapters later, in John 12:35-36, He tells us to, “…walk…so that darkness may not overcome you.” Then He goes on to say that we should, “…believe into the light, so that [we] may become sons of light.” So even though He would eventually leave the world, we should believe into the light and walk in the light. Then we will not be overcome by darkness and can even become sons of light.
Moreover, in Matthew 5:14, He goes further to tell us, “You are the light of the world.” As those who have believed into the light and have received God into our heart as light, we are now the light of world.
As such we must walk in a way that shines forth the light and is not overcome by darkness. Ephesians 5:7-16 instructs us:
7 Therefore do not be partakers with [sons of disobedience] (v. 7).
8 For you were once darkness but are now light in the Lord; walk as children of light
9 (For the fruit of the light consists in all goodness and righteousness and truth),
10 Proving what is well pleasing to the Lord.
11 And do not participate in the unfruitful works of darkness, but rather even reprove them.
12 For the things which are done by them in secret it is shameful even to speak of.
13 But all things which are reproved are made manifest by the light; for everything that makes manifest is light.
14 Therefore He says, Awake, sleeper, and arise from the dead, and Christ will shine on you.
15 Look therefore carefully how you walk, not as unwise, but as wise,
Redeeming the time, because the days are evil.
We are called to be light and salt.
“You are the salt of the earth; but if the salt has become tasteless, how will it be made salty again? It is good for nothing any more, except to be thrown out and trampled under foot by men. You are the light of the world. A city set on a hill cannot be hidden. Nor do men light a lamp, and put it under the peck-measure, but on the lampstand; and it gives light to all who are in the house. Let your light shine before men in such a way that they may see your good works, and glorify your Father who is in heaven” (Matthew 5:13-16).
The rub comes in determining where it is that we draw the lines of separation. We are not to be partakers with those in darkness (Ephesians 5:7), nor are we to participate in the unfruitful deeds of darkness (5:11). Where, then, do we draw the line in terms of our relationships with the lost? We draw the line by the way we choose to live our lives in relationships to one another. An invading army would often destroy orchards and vineyards and take salt and trample it underfoot in the fields so that the land would not yield crops for generations. The risk of being trampled underfoot as a Christian – loosing our light and salt - is that we allow those who hate what we believe to further poison the world around them by using our example against the Gospel.
Shine as Luminaries
Through our life and our walk together we should fulfill our commission: "To open their eyes, to turn them from darkness to light and from the authority of Satan to God, that they may receive forgiveness of sins and an inheritance among those who have been sanctified by faith in Me." Acts 26:18
As the disciples of the Lord, as His continuation on the earth today, we have a responsibility to be the light of the world just as He was. In Matthew 5:14-16, our Lord charged us in this way:
14 You are the light of the world. It is impossible for a city situated upon a mountain to be hidden.
15 Nor do men light a lamp and place it under the bushel, but on the lampstand; and it shines to all who are in the house.
16 In the same way, let your light shine before men, so that they may see your good works and glorify your Father who is in the heavens.
This is a tall order and not one we could or should ever expect to do on our own power or alone. We need to rely on His unfailing grace.
3 "His divine power has given us everything we need for a godly life through our knowledge of him who called us by his own glory and goodness. 4 Through these he has given us his very great and precious promises, so that through them you may participate in the divine nature, having escaped the corruption in the world caused by evil desires.
5 For this very reason, make every effort to add to your faith goodness; and to goodness, knowledge; 6 and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness; 7 and to godliness, mutual affection; and to mutual affection, love. 8 For if you possess these qualities in increasing measure, they will keep you from being ineffective and unproductive in your knowledge of our Lord Jesus Christ. 9 But whoever does not have them is nearsighted and blind, forgetting that they have been cleansed from their past sins." 2 Peter 1:3-11
Paul’s emphasis is not merely upon individual duty to “walk as lights,” but on the task of the church, collectively, to be a light. We need to rely on each other.
In summary, the Christian’s conversion calls for a radically new lifestyle and a new relationship with the world. Jesus is the light of the world, and all who name His name as believers are to walk in the light and to walk as lights, just as He did when He was physically on this earth. To walk as children of light is also to walk in love. If we do no walk as light we will not be walking in love. Love does not “support” the sinner and the expense of righteousness. Love admonishes, rebukes, yes, but like healing light, it seeks to restore.
To walk as children of light is the ultimate calling of the Christian. It is in so doing that we obey and please God. It is in so doing that we glorify God. It is in so doing that the gospel is proclaimed. Walking in the light will, in all cases, glorify God and bring restoration to his people and when lived authentically can result in the salvation of lost souls.
We can begin again, we can separate light and darkness in our lives Let us begin again as we renew our commitment to one another – make our calling and election sure. The light of Christ casts no shadow.