The largest single collection of the Lord’s teachings is what we call the Sermon on the Mount. It is recorded in great detail in Matthew’s gospel, chapters 5-7. In this great discourse the Lord laid the foundation of what would be required of His disciples. Very early in His discussion the Lord used two important images to illustrate the effect He expected His disciples to have on the world. These images are salt and light.
In Mt. 5:13-16 the Lord said, “You are the salt of the earth; but if the salt has become tasteless, how can it be made salty again? It is no longer good for anything, 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 does anyone light a lamp and put it under a basket, 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.”
The imagery of salt and light are powerful illustrations because of what they do and how they work. Salt essentially has three effects. First, it is a preservative. It has long been used to cure meat where there is no means of refrigerating or freezing it. Second, it enhances the flavor of the foods on which it is applied. Many foods, like eggs and potatoes, taste much better with a little salt on them. Third, salt causes thirst. Anyone who has eaten a salty snack food knows this is true. The reason salt has these effects is because it is chemically different from the items on which it is placed. If it were of the same composition as these foods, it would make no difference in them.
Light is just as powerful an imagery. Light enables us to see in situations in which we would otherwise be unable to see. Light facilitates and sustains life on the earth. Without light, life on earth would be impossible. Light also lifts our spirits and often takes away our fears. It has this effect because light dispels darkness. It does so because it is the exact opposite of darkness. Where light shines there can be no darkness, and darkness can only exist where there is no light. The two are mutually exclusive.
When these images are applied to Christians, we can easily see why the Lord used them to refer to His disciples. We are different from the world because our sins have been washed away by the blood of Christ (Acts 22:16). Like salt, we are a preserving agent in the world. God spares the world because of His people, who are trying to lead the lost to salvation. We also enhance the world by our presence in it because of our godly examples. Our godly way of life leads others to thirst for God’s truth, and the salvation that may only be obtained in Christ. We make the world a better place by being salt in it.
In a similar way, as light we shine the good news of Jesus Christ and His salvation into the darkness that has enveloped the world. As we reflect the light of our Lord by our godly lives, we expose sin for what it is, and we show the way to eternal life through Jesus our Lord. We show those who are stumbling in the darkness the narrow path that leads to life. In these ways we make the world a better place by being light in it.
When the Lord used the imagery of salt and light to describe His disciples He didn’t say that he hoped we would be salt and light. Neither did He say we ought to be salt and light. He said we are salt and light. By virtue of having been purchased by His blood we have been made into salt and light by the will of our Lord and Savior Jesus Christ. This is what we are, and this is what we must be in order to please Him.
(Note: The picture above is a salt shaker with an LED light inside it. My son made this to portray the imagery of salt and light)