The Lord told His disciples that they are the salt of the earth and the light of the world (Matthew 5:13-16). What did He mean by this? Most food in those days did not have extra flavoring and spices. Spices were mostly an expensive delicacy. Even the most common spice in the world today - black pepper - was once used as money. Another main commodity is salt. About 200 million tons are produced each year. We think of salt as a way to flavor our food, but until about 100 years ago (before refrigeration) it was a main way to preserve food, especially meat. It is still used that way, especially in canned foods. It was also used as money. The word salary comes from the word salt. Salt in the right amounts is essential to life. It also has many other uses. Actually only about 6% of salt is used in food. It is used in the rituals of many religions, including Judaism. The Israelites were to put salt on their offerings (Leviticus 2:13, Numbers 18:19, Ezra 6:9, Ezekiel 43:24, Mark 9:49). The Dead Sea was called the salt sea, and the area around it was called the valley of salt.
When Jesus said His disciples are the salt of the earth, He then asked the question, "if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men." How can you restore the flavor of salt if it is gone? The salt is the flavor. This has two meanings. The first is individual. If a Christian is not living according to the word of God, of what spiritual benefit are they? The second is general. The church is the only representative Christ gave the world. If the church is not salting the earth, there is no other salt. God has given the church this great responsibility.
2Thessalonians 2:7 says, "For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way." This is speaking about what is restraining the end of the world and the revealing of the antichrist. It is the presence of the church in the world until it is taken up to be with the Lord (1Thessalonians 4:13-17). The church is what is keeping the corruption of the world in check until the Lord returns. If you think the world is in bad shape now (which it is), imagine how bad it would be without the church. The church is not perfect, but the haters of God should not blame the church for the state of the world. The true church is striving to make a difference for good.
The church is also the light of the world. When God made the heaven and the earth, the earth was covered with water and in darkness at first. Then God said. "Let there be light (Genesis 1:3)." Light represents God Himself. "This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all (1John 1:5)." "Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life (John 8:12)." Also see John 9:5 and John 12:46. As the body of Christ, the church is the light of the world. A light does not do anyone any good unless it illuminates an area so they can see. People do not put their light sockets under their furniture or behind their walls. They strategically place them where they can bring the most light to the room. The people of God need to be witnesses to those around them, so they too can see what God has shown them.
God meant for His church to be effective in showing God to others so they can know Him too. When we have a consistent relationship with Him, it is to our benefit, and the benefit of all with whom we interact (John 15:1-16). Christians can only completely fulfill their destiny in God when they are leading others to Him. If we bury it, we will lose it (Matthew 25:14-30). The reward is to the producers. While we cannot control the decisions of others, we can do our part by being the salt and light.