If the beatitudes leave the impression that believers are to play a somewhat passive role in society (“meek . . . merciful . . . peacemaker”), the following verses (Matt. 5:13-16) describe the active role they are to play. Jesus tells his followers they are to be the “salt of the earth” (v. 13) and the “light of the world.” What do these two metaphors suggest?
In the ancient world salt, in addition to being a seasoning, was a purifier and preservative. As believers live out the beatitudes in their daily lives they will permeate the world and retard its moral and ethical decay. One of the most noticeable things about salt is its essential difference from the medium in which it is placed. If Christians were “salty” they wouldn’t look like the world, but would affect it as a change agent. Every time you forget to put the salt in a dish for dinner, everyone at the table has a comment on how dull the food tastes. They know that salt changes things and if nothing is happening – “You forgot to add the salt!” If a group of believers do not change in some way the larger society of which they are a part, it would be reasonable to conclude that they weren’t the salt they claimed to be.
In the same say, followers of Jesus are to be “the light of the world.” Light has as its major function, illumination. Without light the world lives in darkness. Both here and in John, Jesus declares, “I am the light of the world” and, “If you follow me you won’t have to walk in darkness” (v. 14; John 8:42 NLT). The purpose of light is obvious and needs no discussion. Consider the impropriety of lighting a lamp and then covering it up. Talk about wasted energy. Think about it for a minute: If you build a city on a mountaintop there is simply no way to hide it. Everybody can see it. In the same way, if believers claim to be a bright city on the hillside and no one can find it, it’s obviously not there. If you can’t taste the salt or see the city they are both imaginary..
It is interesting to note that Jesus puts it this way: “Let your light shine.” Remember, we’re not the light, but simply lamps on the lamp stand. When we let God shine through us the world will see our good deeds and give praise to our Father in heaven (v. 16). Good deeds provide light in the world because they illuminate what God had in mind in the first place, i.e., to bring people out of the darkness of sin and into the glorious light of eternity. And the best way to do it is to live it out! As we used to sing in a different context, “Shine, Baby, shine!”