Jesus said, “You are the salt of the earth; but if the salt loses its flavor, how shall it be seasoned? It is then good for nothing but to be thrown out and trampled underfoot by men.” (Matthew 5:13)
This saying puzzles modern Bible readers because when they think of salt, they think of that pure table salt in the cupboard which never seems to go stale.
This saying might also confuse the more scientific-minded Christian since they know that Sodium Chloride (NaCl) is a chemically stable compound.
In order to understand Jesus’ words, the modern Bible reader needs to realize that the most common (i.e., inexpensive) salt in ancient Palestine was not made through the evaporation of sea water, but rather harvested near the shores of the Dead Sea.
Salt taken from this area was mixed with other materials and minerals. If this impure salt was stored improperly or exposed to moisture, the highly soluble NaCl (actual salt) would leech away; leaving behind only the tasteless and useless impurities.
Answered by Pastor Christian McShaffrey