'Saltness' in the Bible

“You are the salt of the earth; but if the salt has lost its taste (purpose), how can it be made salty? It is no longer good for anything, but to be thrown out and walked on by people [when the walkways are wet and slippery].

where their worm [that feeds on the dead] does not die, and the fire is not put out.

“Therefore, salt is good; but if salt has become tasteless, with what will it be seasoned?