Image: Jill DeHaan

My first job after graduating from Clemson University was as a quality control chemist at a small pharmaceutical company in Atlanta. It was a great job, but I was far too extroverted to enjoy a career in a lab. Initially, I had enrolled in college with the intention of becoming a physician, but after a spiritual awakening during my senior year, I made a decision to attend seminary instead of medical school. As a consequence, I learned the Bible with the sciences in mind—which has been a continual source of insight into my reading of Scripture.

For example, I was recently doing some research for a lecture on Luke 14:34–35. When I read Jesus’ words—“Salt is good, but if it loses its saltiness, how can it be made salty again?”— I decided to look into what Jesus’ original audience might have understood about salt when Jesus taught them to be “the salt of the earth.” When I discovered that salt was used as a fertilizer in Palestine, it permanently changed how I viewed the command to love my neighbor. What previously had been a somewhat strange charge by Jesus to be “salty” became a source of inspiration for Christian life and mission.

You are ‘salt for the soil.’

According to specialists in environmental science and soil chemistry, salt has been a major method of fertilizing soil for centuries.

An old article in the journal Biblical Archaeology, “Salt, Soil, Savior,” stands the test of time. Eugene P. Deatrick, former head of the soils department at West Virginia University, argued that in Matthew 5:13, Mark 9:50, and Luke 14:34–35, Jesus was speaking not primarily of salt’s household use but of its agricultural use. According to Deatrick, several kinds of salt are found in Palestine that are different from the kind we’re familiar with. There is rock salt, salt evaporated from Dead Sea water, salt pits (Zeph. 2:9), and more. Additionally, Deatrick writes that “agricultural literature abounds in references to the use of salt as a fertilizer.” In quoting another source, he noted that “the value of salt in small quantities appears to have been known in ancient times—Cato, Virgil (and others) record its power of improving herbage of pastures.”

As Deatrick mentioned, agriculturalists have long recognized the value of salt as a fertilizer. A prize-winning essay on the valuable properties of salt for agriculture written by Robert Faulk, a contemporary of Deatrick’s, recognizes the long lineage of the agricultural use of salt. He states that the “ancient Hebrews already applied it 2,000 years ago in Palestine,” citing 2 Kings 2:21 and Luke 14:34. It’s fascinating that this essay on the agricultural use of salt specifically refers to Luke 14:34 to make its case, indicating that Jesus is talking about an agricultural rather than a culinary phenomenon.

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When Jesus spoke about salt in Matthew 5:13, Mark 9:50, and Luke 14:34–35, he was referring to several varieties of salts used in the first century. These salts were unlike the modern table salt (sodium chloride) in our kitchens. The salts in Jesus’ day were mixtures of chlorides of sodium, magnesium, and potassium, with very small amounts of calcium sulfate (gypsum). Some of these would dissolve more quickly than others, while some were better able to withstand the elements. These hardier, “saltier” salts were generally more valuable in an agricultural context because that meant their benefits would last longer.

When Jesus talked about salt losing its “saltiness” or “savor,” it refers to a process in which the compounds of salts naturally disintegrate over time. Disintegrated salt loses a small amount of gypsum, which changes its “saltiness.” This change in saltiness makes it a less effective fertilizing agent. So when Jesus talked to his followers about losing their saltiness, he was talking about losing their fertilizing properties, their ability to bring about life and growth.

If we are supposed to be salt in the agricultural sense, that means we are supposed to get messy and to go where nothing is growing right now.

If Jesus wasn’t talking about table salt but fertilizing salt, that means that his reference to “the salt of the earth” in Matthew 5:13 can just as easily be translated as “salt for the soil.” This makes better sense of Jesus’ words in Luke 14:34–35: “Salt is good, but if it loses its saltiness, how can it be made salty again? It is fit neither for the soil nor for the manure pile; it is thrown out.”

The reference to the manure pile has long been a source of confusion when viewing salt as seasoning in these passages. Jesus’ saying makes more sense when we realize that salt maintains the fertilizing properties of dung. It is common knowledge today that salt can be used to preserve food, but it’s been used as an agricultural preservative for fertilizer for centuries as well. A 19th- century agricultural reference volume notes that “Salt is applicable in all cases in which . . . fermented dung cannot be carted at once to land. Covering the heap with salt will be found a cheap and effective means of checking fermentation.” Salt keeps dunghills from rotting and becoming useless as fertilizer while enhancing the fertilizing properties of dung. This centuries-tested agricultural understanding of salt fits these passages and the ancient world much better than interpreting the salt as table salt—even if all this talk of fertilizer and manure makes us a bit squeamish.

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In further research, I discovered that not only did the ancient Hebrews use salt in this way, but so did the Chinese and early Romans. Salt was used in arid places to help soil retain moisture, destroy weeds, make stubborn soils easier to till, and make sour grass sweeter and more appealing to cattle. In some soils, salt keeps rust from wheat, and blight from potatoes. When applied properly, salt will kill surface weeds while allowing more deeply rooted plants and grass to thrive. And when rain or irrigation allows salt to permeate soil, the salt chemically frees vital minerals and nutrients in the soil, allowing them to nourish plants.

While this may be a foreign concept to us in the West, it is still well-known in other parts of the world. For example, the Philippine Coconut Authority recently released a technology guide sheet for farmers titled, “SALT (Sodium Chloride): An Effective and Cheap Fertilizer for High Coconut Productivity.” The guide notes that salt accelerates crop growth and development, increases crop yield, minimizes damage to plants, and promotes environmental sustainability. According to the guide, between 1991 and 1997, farmers who fertilized with salt had a yield increase of 125 percent over unfertilized coconuts.

The Power of Salt

What if we were to listen to the teaching of Christ like the coconut farmers in the Philippines—or the ancient people of Palestine—rather than as modern Westerners who only use salt to spice up their food? How might a distinctly agricultural viewpoint open up new vistas in Jesus’ teaching here?

Deatrick’s paraphrase of Jesus’ teaching demonstrates how this understanding makes the message much more powerful: “You are (like) the salt for the soil, a stimulant for growth. If you become like the savorless salt, no longer good for anything, how will the gospel of the kingdom be preached throughout the whole world?”

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Christians are not here to merely season or preserve the world from decay. The followers of Jesus Christ are sent on a mission to stimulate growth in the parts of the world that are barren, and to be mixed into the manure piles of the world so that God can use that fertilizer to bring new, virtuous life. But if those same followers are not committed to the radically countercultural message of Jesus Christ, they lose their “saltiness,” which is the unique witness to the power of the gospel that brings the kingdom of God to the messes of the world, stimulating life and growth. If we lose our “saltiness,” we are “no longer good for anything” and cannot be the agents of change that Jesus intended for his followers to be (Matt. 5:13).

The call of the salty is the call to move toward the broken.

If the agricultural use of salt makes barren soil easier to till, facilitates the absorption of other vital nutrients by plants, and maintains and enhances the fertilizing capacity of manure, then Jesus is calling us to something extraordinary and countercultural. If we are truly supposed to be salt in the agricultural sense, that means we are supposed to get messy and go where nothing is growing right now. Instead of going where things are bright, new, and exciting, we have a call to explore opportunities that will probably not make sense in the eyes of “normal” people.

People may say things like, “She graduated from Harvard with a degree in history—why is she teaching seventh grade in rural West Virginia?” Or, “He was a varsity athlete with the talent to go pro; why did he choose to stay home and support his divorced mother and three siblings instead?” Or, “They both have promising careers; why do they spend so much time working with special needs adults in their community when they could be making a difference in the corporate world?”

In the face of these questions and criticisms, being salt and light for the good of the world sets us free to love our neighbors and not feel like we’re missing out or “not living up to our potential.” When we realize we are fertilizer, we measure our value by the growth of others, not by our comfort or vocational success. Moreover, we also recognize that we need to be scattered where the soil most needs fertilizing. We need to be in close relationships with people who do not know or believe the gospel so that new life in Christ might grow where there is now only barren soil.

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An agricultural understanding of Jesus’ call for us to be the “salt of the earth” sheds light on some of the most important issues facing Christians today. Questions about evangelism, justice, cultural engagement, and social responsibility gain a surprising clarity when considered in terms of promoting the life and flourishing of others. This view of the “salt of the earth” encourages us to discern where God is leading us by considering how our gifts and interests intersect with the barren places and the manure piles of the world.

Manure piles are all around us—they come to us in the form of devastated lives. There are lifeless sections of soil in every small town, big city, and suburb in America. There are friends and family members whose lives are in a state of disaster. Financial problems, addictions, oppression, injustice, poor decision making, ignorance, or outright rejection of the gospel are all too common. A whole host of messy problems plague the lives of those we care about.

The call of the salty is the call to move toward the broken so that they may meet God and be set free to become who God wants them to be. As salt, we are intended to bring life and flourishing out of decaying manure piles and arid soil where nothing grows—spheres of society that are dead, barren, or rotting because Christians are not there. Wherever the world is not the way God in his goodness intended it to be, that is where Christians should be encouraging and training one another to go. The good news is that we don’t have to go that far to find opportunities to be salt.

No matter where God sprinkles us, grace gives us the means and love gives us the motive to live salty lives consistent with Jesus’ teaching for the benefit of others and the glory of God.

ANTHONY B. BRADLEY is associate professor of religious studies at The King’s College in New York City. His most recent book is Something Seems Strange: Critical Essays on Christianity, Public Policy, and Contemporary Culture (Wipf and Stock).

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