"Keep your shoulder to the harness, your nose to the grindstone, your hand to the plow and your eyes on the goal...” which, as brother Robert Turner once observed, is good advice but a mighty uncomfortable position to maintain. It is not uncommon to find people mixing figures in such a way as to present an impossible situation, and, consequently, a truth gets lost in confusing terminology.
Some folks talk about being citizens in the vineyard or branches in the kingdom and when they do so, they destroy the effectiveness of those analogies. Jesus frequently employed figures in his teachings. Two are found in Matthew 5:13-16, which are designed to teach lessons about discipleship -- "Ye are the salt of the earth...ye are the light of the world." It would be totally destructive to the meaning to say that disciples are to let their salt shine or that they are to have the savor of light.
When Jesus said, "Ye are the salt of the earth," He intended to convey a lesson that disciples are salt in a spiritual sense and, in comparing physical and spiritual, teach that disciples are to be a good spiritual influence. Anyone knows that saltless salt, salt that has no taste or savor, is valueless in influencing the taste of food. Hence, if a disciple is not salty, he is worthless.
Next, Jesus said, "Ye are the light of the world...", but don't mix the figures. There are some truths about light which have nothing to do with salt but which, as salt does, correctly illustrate the same truths about influence. First, it is impossible to hide a city set on a mountain, because the very nature of light is that it is seen. Second, it would be totally incongruous to light a candle and put it under a bushel, because the very purpose of light is illumination. Men do not cover up light – they let it shine.
But remember that influence can be evil as well as it can be good. Paul said, "Be not deceived: evil communications (literally, "evil associations") corrupt good manners" (1 Corinthians 15:33). He had previously used the word "leaven" to illustrate the permeating influence of fornication in the church at Corinth (1 Corinthians 5:6).
Jesus extended the "light" figure by saying, "Let your light so shine before men that they may see your good works, and glorify your Father which is in heaven" (Matthew 5:16). What kind of influence do we have on the world? If it is not a good impact, then it will be a bad one. Are we salty? Are we
Illuminating? Let's be conscious of the influence that we exert that God may be glorified.