“You are the salt of the earth; but if the salt has become tasteless, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled under foot by men. (Matthew 5:13)
In Matthew 5:13-16 Jesus is talking about influence. He’s talking about how you and I affect the world. And in the Sermon on the Mount, at this point, He is saying, “You who are characterized by Beatitude-quality life, you who are the sons and daughters of the kingdom are the salt and the light of the world to influence the world for good and for God.” Our Lord is calling on us to influence the world we live in, just as He was those disciples gathered with Him as He preached to the multitude.
Adapted from message by John MacArthur “You Are The Salt Of The Earth”