“Ye are the salt of the earth: but 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” (Matthew 5:13).
“Not only did the Hebrews make general use of salt in the food of both man and beast, but they used it in their religious services as an accompaniment to the various offerings presented on the altar. . . The meaning which the salt, with its power to strengthen food and preserve it from putrefaction and corruption, imparted to the sacrifice was the unbending truthfulness of that self-surrender to the Lord embodied in the sacrifice, by which all impurity and hypocrisy were repelled.” Unger’s Bible Dictionary
“Mankind, lying in ignorance and wickedness, were as a vast heap, ready to putrefy; but Christ sent forth his disciples, by their lives and doctrines to season it with knowledge and grace. If they are not such as they should be, they are as salt that has lost its savour. If a man can take up the profession of Christ, and yet remain graceless, no other doctrine, no other means, can make him profitable. Our light must shine, by doing such good works as men may see. What is between God and our souls, must be kept to ourselves; but that which is of itself open to the sight of men, we must study to make suitable to our profession, and praiseworthy. We must aim at the glory of God.” – Matthew Henry
According to this explanation, which I consider to be the right one, Jesus was referring to the use of salt as a preservative. It was the only substance in Bible times that could prevent food from putrefying. Jesus applied this metaphorically to Christians as the only ones who could preserve members of the society around them from going rotten, falling into sin and condemnation.
OK. So now, according to Matthew Henry’s metaphor, we have this great heap of humanity beginning to putrefy. Somewhere else, no doubt upwind, we have this heap of salt. How does this fit with Jesus’ parable? Is the salt doing any good if it is not applied where the problem exists?
It isn’t going to do any good to that putrefying mass either if we apply a little of the putrefaction to ourselves and to our message in an attempt to gain a hearing. The Bible tells us we need to keep ourselves unspotted from the world. If that means anything at all, it means that any hint of pride or a holier-than-thou attitude will cause our saltiness to lose its savour.
The truth is that we are just as prone to putrefaction as any other human and our saltiness is only the product of the grace of God in our lives as we submit ourselves to the leading of His Holy Spirit. Then in humility we can mingle with the people of the world and the salt within us will here and there bring purification and healing to others.
“Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another” (Mark 9:50).