You are the salt of the earth.
But if the salt loses its saltiness,
how can it be made salty again?
It is no longer good for anything,
except to be thrown out and trampled by men.
The Salt of the Earth.
What a concept. Just think of all of the things that would have come to the listeners minds. Salt is a huge necessity during those times: it was valuable, it was a preservative, it was a cleanser, and my favorite, it was a flavor enhancer. As long as it was good.
Here Jesus tells these people how they should be in this world. Oswald Chambers says,
"Some modern teachers seem to think our Lord said, You are the sugar of the earth, meaning that gentleness and winsomeness without curativeness is the ideal of a Christian."
We are to be effective in this world. We are to be effective in our work, in our families, and with our friends. And the effectiveness should look like the first few verses of this chapter. If you fulfill those things, then you will be the salt of the earth.
But if you lose that saltiness, then you will be uneffective, useless, and cast out.