Expositor's Bible Commentary Commentary Matthew 5:13

"Ye are the salt of the earth: but if the salt have lost its savor, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out and trodden under foot of men." — Matthew 5:13 (ASV)

In this verse and v.14, “You” is emphatic—“You, my followers and none others, are the salt of the earth.” Salt was used in the ancient world to flavor foods and even in small doses as fertilizer. Above all, salt was used as a preservative. Rubbed into meat, a little salt would slow decay. Strictly speaking salt cannot lose its saltiness; sodium chloride is a stable compound. But most salt in the ancient world derived from salt marshes rather than by evaporation of salt water, and thus contained many impurities. The actual salt, being more soluble than the impurities, could be leached out, leaving a residue so dilute it was of little worth.

The question “How can it be made salty again?” is not meant to have an answer. The point is that if Jesus’ disciples are to act as a preservative in the world by conforming to kingdom norms, they can discharge this function only by retaining their own virtue.