Two of the most important uses of salt is to improve taste and to preserve food. When Christ old us we are the salt of the earth, he meant that we are here to save the world, just as he saved us. That is a heavy responsibility, for as Christ said, to whom much is given, much is expected. We have been given salvation, and we are expected to share it with as many people as we can.
But what if we don't follow through with this awesome responsibility?
Here is the passage from Matthew:
You are the salt of the earth. But if the salt lose its savour, wherewith shall it be salted? It is good for nothing any more but to be cast out, and to be trodden on by men.St. Augustine, in his great wisdom, gives us a clear understanding of what it means to be the salt of the earth, how it is possible to lose the power of savoring others and what happens when we lose our savor:
You are the light of the world. A city seated on a mountain cannot be hid. Neither do men light a candle and put it under a bushel, but upon a candlestick, that it may shine to all that are in the house. So let your light shine before men, that they may see your good works, and glorify your Father who is in heaven.
Do not think that I am come to destroy the law, or the prophets. I am not come to destroy, but to fulfill. For amen I say unto you, till heaven and earth pass, one jot, or one tittle shall not pass of the law, till all be fulfilled. He therefore that shall break one of these least commandments, and shall so teach men, shall be called the least in the kingdom of heaven. But he that shall do and teach, he shall be called great in the kingdom of heaven.
No other human being can hurt us spiritually. We can only do that to ourselves by choosing the physical temporary things of this world over the spiritual and eternal things of heaven. As Christ said, "fear ye not them that kill the body, and are not able to kill the soul: but rather fear him that can destroy both soul and body in hell." (Matthew 10:28) Lent is all about choosing the spiritual over the physical. We have 40 days (plus Sundays) in which to learn these lessons and hopefully apply them for the rest of the year, and the rest of our physical lives, as well.The Lord would have us understand how that men do lose their power of savouring others with righteousness when they are willing to place their eternal welfare in jeopardy for the sake of any temporal advantage, like as attainment of ease or luxury, or escape from suffering or toil. For that which is eternal, unlike things of this world, can neither be bestowed by men, nor by them taken away. [St. Augustine says here that if we lose our savor, we will have no one to blame but ourselves because no other human can take it from us.] Hence, when he asketh : If the salt have lost his savour, wherewith shall it be salted? he would have us understand the question to be : If ye, by whom mankind is preserved from corruption, be willing to lose the kingdom of heaven so as to escape trials or persecutions in this world, who is there to preserve you from corruption, seeing ye are they that God hath chosen to preserve all others from corruption? [A heavy judgment will be placed on all to whom God has given his Spirit and who then, like Esau choosing a pot of lentils over his birthright, choose earthly things instead of heavenly.]
Those that should be the salt of the earth, but have lost their savour, are thenceforth good for nothing, but to be cast out, and to be trodden under foot of men. But no one that suffereth persecution is truly said to be trodden under foot of men. Rather, that one is truly trodden under foot of men who through fear of persecution hath lost the savour of righteousness. For no one can be trodden upon, unless he be beneath him which treadeth upon him. And certainly no one who hath his heart in heaven, no matter how grievously he doth suffer in his body on earth, is rightly said to be beneath anyone who misuseth him.