“if the salt has become tasteless.” Some commentators say that Jesus is stating something that is unnatural (that salt could become unsalty) to catch people’s attention and make them realize that while salt cannot become unsalty, believers can stop serving God and thus become “unsalty,” and if that happens, how could they become salty again? However, that is much less likely than the fact that biblical salt in Israel came from places such as the salt marshes around the Dead Sea (cp. Ezek. 47:11), and salt that had evaporated from the sea and was sitting on the soil was often mixed with dirt and other minerals such as gypsum. Thus it could happen that over time a block of “salt” could have the actual salt leached out of it, leaving the “salt” unsalty and worthless. At that point it could not be “resalted,” it could only be thrown out as worthless. Similarly, if a believer is exposed to the world and allows the “salt” in them to be leached out, they are in danger of being worthless for the work of the kingdom.
Matthew 5:13 is well explained by William McClure Thomson (1806-1894). Thomson did missionary work in the biblical lands for over 30 years. He acquired a vast knowledge of the customs of the land, many of which had not changed or not changed much since the biblical period. He was used as a guide by some noted biblical scholars, and traveled with Edward Robinson, one of the founders of modern Biblical archeology, on Robinson’s second tour of the Holy Land. He was beloved by the locals, who took notice of the broad-brimmed hat he always wore and called him “Abu Tangera,” which means “father of a cooking pan” because of the shape of his hat. His famous book, The Land and the Book was first published in 1859, and for several decades was the second-best selling book in America after Uncle Tom’s Cabin. It was framed around a pilgrimage around the Bible Lands that he took in 1857. As well as describing the places he saw, Thompson weaved many customs and personal experiences into the book that make it invaluable to Bible Study, especially since many of the customs he describes are biblical but are no longer practiced. Thompson’s 1850’s English can make the book somewhat challenging in places, but it can be understood. About salt losing its saltiness, Thompson wrote:
“It is plainly implied that salt, under certain conditions so generally known as to permit him [Jesus Christ] to found his instruction upon them, did actually lose its saltness; and our only business is to discover these conditions, not to question their existence. Nor is this difficult. I have often seen just such salt, and the identical disposition of it that our Lord has mentioned. A merchant of Sidon having farmed of the Government the revenue from the importation of salt, brought over an immense quantity from the marshes of Cyprus—enough, in fact, to supply the whole province for at least twenty years. This he had transferred to the mountains, to cheat the Government out of some small percentage. Sixty-five houses in June—Lady Stanhope’s village—were rented and filled with salt. These houses have merely earthen floors [i.e., have only dirt floors], and the salt next [to] the ground in a few years entirely spoiled. I saw large quantities of it literally thrown into the street, to be trodden underfoot of men and beasts. It was “good for nothing.” Similar magazines [storehouses] are common in this country, and have been from remote ages, as we learn from history both sacred and profane; and the sweeping out of the spoiled salt and casting it into the street are actions familiar to all men.
It should be stated in this connection, that the salt used in this country is not manufactured by boiling clean salt water, nor quarried from mines, but is obtained from marshes along the sea-shore, as in Cyprus, or from salt lakes in the interior, which dry up in the summer, as one in the desert north of Palmyra, and the great Lake of Jebbul, south-east of Aleppo. The salt of our Sidon merchant was from the vast marches near Larnaca. I have seen these marshes covered with a thick crust of salt, and have also visited them when it had been gathered into heaps like hay-cocks [haystacks] in a meadow. The large winter lake south-east of Aleppo I found dried up by the last of August, and the entire basin, further than the eye could reach, was white as snow with an incrustation of course salt. Hundreds of people were out gathering and carrying it to Jebbul, where the Government stores were kept.
Maundrell, who visited the lake at Jebbul, tells us that he found salt there which had entirely “lost its savor;” and the same abounds among the debris at Usdum, and other localities of rock-salt at the south end of the Dead Sea. Indeed, it is a well-known fact that the salt of this country, when in contact with the ground, or exposed to rain and sun, does become insipid and useless. From the manner in which it is gathered, much earth and other impurities are necessarily collected with it. Not a little of it is so impure that it cannot be used at all; and such salt soon effloresces and turns to dust—not to fruitful soil however. It is not only good for nothing itself, but it actually destroys all fertility wherever it is thrown; and this is the reason why it is cast into the street. There is a sort of verbal verisimilitude in the manner in which our Lord alludes to the act—“it is cast out” and “trodden underfoot;” so troublesome is this corrupted salt that it is carefully swept up, carried forth, and thrown into the street. There is no place about the house, yard, or garden where it can be tolerated. No man will allow it to be thrown on to his field, and the only place for it is the street; and there it is cast, to be trodden under the foot of men” (W. M. Thompson, The Land and the Book, Baker Book House, Grand Rapids, MI, reprinted 1973. Chap. XXVI, “Kersa-Tiberias,” Pps. 381-382).
“thrown out into the street.” The words “into the street” are added for clarity. Although the text just says “thrown out,” to most people today that means “thrown into the trash.” But there were no trash cans in the biblical world, and no trash collectors. “Thrown out,” meant “thrown out of the house into the street,” and that happened with most unwanted things. For example, in the Roman world, sewage was almost always simply thrown into the street, which was a major reason for the horrible stench in the cities, the prevalence of disease, and why it was important to wash one’s feet upon entering a house (and why that job was given to the lowest slaves in the household). Salt that had lost its saltiness was thrown out into the street and was trampled on by the street traffic.