Mark 9:50: Saltless Salt?
One can use salt to season meat or bread, but if the salt that one was going to use loses its saltiness, what can be used to season it?
But how can salt lose its saltiness? If it is truly salt, of course, it must remain salt and retain its saltiness. But probably in the ordinary experience of Galilean life, salt was rarely found in a pure state; in practice it was mixed with other substances, various forms of earth. So long as the proportion of salt in the mixture was sufficiently high, the mixture would serve the purpose of true salt. But if, through exposure to damp or some other reason, all the salt in the mixture was leached out, what was left was good for nothing. As Luke, in his amplified version of the saying, puts it, "it is fit neither for the land nor for the dunghill" (Lk 14:35 RSV). It might have been thought that the dunghill was all that it was fit for, but Jesus may have used a word that meant "manure": "it is no good for the land, not even as manure." Matthew says, "It is no longer good for anything, except to be thrown out and trampled by men" (Mt 5:13), that is to say, people throw the useless stuff out into the street.
The figure of insipid salt appears in the words of the rabbis, with reference (it seems) to Israel's role as the salt or purifying agency among the nations of mankind. Matthew's version of Jesus' saying begins with the words "You are the salt of the earth" (Mt 5:13) addressed to his disciples. This implies that the disciples have a particular function to perform on earth, and if they fail to perform it, they might as well not exist, for all the good they will do. In what respect they are said to be salt is not specified, so the nature of their function has to be inferred from the context and from what is known of the effect of salt. They may be intended to have a preserving and purifying effect on their fellows, or to add zest to the life of the community, or to be a force for peace. The idea of an insipid Christian ought to be a contradiction in terms. One way in which the quality of saltiness can be manifested is in one's language. "Let your conversation be always full of grace, seasoned with salt," Paul writes to the Colossians (Col 4:6), where the "salt" seems to be that ready Christian wit or wisdom (specially apt in the answering of questions about the faith) which is far removed from the slanderous and unsavory talk deprecated earlier in the same letter (Col 3:8).
Since the disciples are spoken of as the salt of the earth in the same context of the Sermon on the Mount in which they are also spoken of as the light of the world and a city set on a hill (Mt 5:14), it is evidently their public life that is in view. They must be seen by others as living examples of the power and grace of God, examples which others are encouraged to follow.
Mark adds some other sayings in which salt figures. These "salt" sayings follow the warning that it is better to enter into life maimed than to be consigned with all one's limbs to the "Gehenna of fire" (Mk 9:43-48). A transition between that warning and the "salt" sayings is provided by the sentence "Everyone will be salted with fire" (Mk 9:49). The fires which burned continuously in the Gehenna or municipal garbage dump south of Jerusalem reduced the risk of disease, which might have arisen from the decomposing organic matter; fire had a purifying effect, as salt also had. The point of Jesus' words in this "transitional" sentence may be that the fire of persecution will have a purifying or refining effect in the disciples' lives (see 1 Pet 1:6-7). Some texts of Mark append here a quotation from Leviticus 2:13 (where the reference is more particularly to the cereal offering): "Season all your grain offerings with salt." This clause is probably not original in this context, but those who were responsible for inserting it (being moved to do so probably by the common theme of salt) may have intended it to mean "Every Christian, by enduring persecution, will be cleansed thereby and so become a more acceptable offering to God."
Then, after the saying about the salt that has lost its saltiness, Mark concludes this series of sayings with "Have salt in yourselves, and be at peace with one another." Again, we should understand this injunction better if we knew the situation in which it was originally spoken. "Have salt in yourselves" might mean "Have salt among yourselves" and might refer to the eating of salt together, an expression of fellowship at table and therefore of peaceful relations. If this is so, then "be at peace with one another" is a nonfigurative explanation of "have salt among yourselves." But we cannot be sure.