The symbolism of salt
Salt is the earthy equivalent of fire; hence Deuteronomy describes God cursing the land in terms of his burning it “with sulfur and salt…like the overthrow of Sodom and Gomorrah, Admah and Zeboim, which Yahweh overturned in his anger, and in his fury” (Dt 29:23). Indeed, even the crystalline structure of salt is a kind of “solid translation” of flames into hard, straight lines.
Like fire, salt in excess represents judgment or barrenness — but in proper proportion it seasons and cultivates. You see this dual use in the parable of the salt:
Salt is good, but if the salt becometh tasteless, with what shall it be seasoned? It is fit neither for land nor for dunghill — they cast it out. (Lk 14:34–35)
A small amount of salt would fertilize the soil; a larger amount would sterilize a dunghill. Since we ourselves are dirt (Gen 2:7) — some of us good soil, and some of us worthless (cf. the parable of the sower) — so in Mark’s telling, Jesus speaks of our being “salted with fire”:
And if thine eye may cause thee to stumble, cast it out; it is better for thee one-eyed to enter into the kingdom of God, than having two eyes, to be cast to the hell of fire — where their worm is not dying, and the fire is not being quenched; for all with fire shall be salted. (Mk 9:47–49)
Here, as I take it, “all” really does mean all: the choice is this:
You can be kindled into bearing fruit in this life, through the purification and “fertilizer” of suffering loss — and thus enter the kingdom of heaven;
You can be seared and made “sterile” in hell — becoming eternally fruitless and unable to bring forth anything of value — through the scorching of God’s eternal judgement.
This also explains why Lot’s wife turned into a pillar of salt: she became a physical manifestation of the judgment poured out on Sodom when she “looked back” (Gen 19:26). We go where we look, and we become what we worship.1
The connection between salt and soil is also why you would rub salt on a newborn (Ezek 16:4); while the connection between salt and purity is why sacrifices had to be salted (Lev 2:13; Ezek 43:24), and why it was added to the temple incense to make it pure and holy (Ex 30:35).
Meanwhile, our speech should be seasoned with salt (Col 4:6) — and we ourselves are salt (Mt 5:13) — in that all these images are gathered up in the Christian, and one more added: savor.
Just as fire transforms an inedible mixture of ground seed and water into tasty bread; or an unappetizing chunk of cow muscle into delicious steak (you even want a sear on it)…so salt, as earthy fire, adds enhancement on top of transformation. We are to be transformed by the fire of the Holy Spirit working on us through the fiery Word of God — and then we, as “fire men,”2 cleanse and add savor to the world through the salt of our own words.
Having learned the pattern in the sanctuary, we are to go out and serve the land as purifiers, fertilizers, and flavor-enhancers: cleaning, cultivating, and transforming it until the raw ingredients which God gave us are worthy to be returned to him as a well-cooked meal — a sweet savor unto the Lord.
This is something I have written on extensively over at Discipleship & Dominion; see especially Look where you want to go, and How we spend our attention is worship…or idolatry.
We are transformed into the image of Christ, who is depicted as a “fire man” in scripture; indeed, the word “man” in Hebrew is related to the word “fire.” I cover this in some detail, starting around 32:00, in episode 7.5 of season 1: