This world is not our home, so why are we here? How are we to bide our time in this life? As Christians, we are not of this world, but we are in it. As citizens of Christ’s kingdom, our character and conduct in this world should be in stark contrast to those who are not in His kingdom. In the Sermon on the Mount, the Lord Jesus, the Master Teacher and Preacher, teaches us how we are to behave in His kingdom in a way to evangelize, enrich, and preserve the world in which we live. Christ was a master of analogy, taking the ordinary stuff of life to teach vivid and vital lessons. In Matthew 5:13-14, the Lord uses two metaphors to illustrate the believer’s mission on earth. Both teach that Christians are different from the world and that their presence in the world should be obvious.

Jesus said, first of all, “Ye are the salt of the earth.” Notwithstanding the warnings of modern medicine regarding the dangers of its overuse, the Lord said, “Salt is good” (Luke 14:34). The presence of salt always makes a difference; it is a foreign substance that affects its environment for good. Salt seasons (Job 6:6; Col. 4:6); it gives taste to the tasteless. It improves the quality of its surroundings. The presence of Christians, who bear witness of Christ, ought to make any place a better place.

Salt also preserves (Lev. 2:13; Num. 18:19; 2 Chron. 13:5). Were it not for the remnant (an Old Testament word designating believers), God would have destroyed Judah as He did Sodom and Gomorrah (Isa. 1:9). So the very pres­ence of Christians in an evil world is an influence for good that can retard the corruption, displaying God’s goodness designed to lead sinners to repentance (Rom. 2:4).

Perhaps most significantly in this context, salt purifies (2 Kings 2:21). Salt can function as an antiseptic. As a purifying agent, salt will aggravate. Salt in a wound is going to smart, but it begins a process to retard decay and infection. Similarly, the world in which we live is rotten and corrupt. The disease of sin is festering and spreading in epidemic proportions. Christians with the message of the gospel of Christ have the only remedy; it is only the gospel that can transform something putrid into something pure. So as the salt of the polluted earth, it is imperative that we make our presence known with a pure witness of the gospel.

Changing the analogy but not the point, Jesus said, “Ye are the light of the world.” Just as the presence of the salt is obvious, so is the presence of light. As salt was radically different from the corrupt world, so light is radically dif­ferent from darkness. In fact, light and darkness are mutually exclusive; they cannot exist together. The truth of the matter is that we used to be darkness, but now we are light in the Lord with the duty to walk as children of light (Eph. 5:8). The light that we shine is not self-generated but reflective of Christ, who is inherently light. What was true of the Baptist is true for every Christian:

He was not that Light, but was sent to bear witness of that Light.John 1:8

As we live, by the Spirit’s grace, as lights in the world, two things will happen. First, light will expose what is in the dark. It’s not a pleasant thought, but living as lights in a world that loves darkness because of their evil deeds is like turning on the light and seeing roaches scamper across the kitchen floor. Shining the light of God’s Word will identify the sins of men and society from which they must repent or face the consequences of everlasting and outer darkness.

Second, the light shows the way out of darkness. There is something hopeful about the sight of light in a dark place. The beacon that will direct sinners out of darkness to marvelous light is Christ. As lights, we must shine His message. Bearing witness to Christ in a dark world is why we are here.

The bottom line: As salt and light, we are different from the world and our presence in the world should be obvious. Is it?