Matthew 5:13-20 Commentary

How does salt lose its saltiness? Thinking about the salt as it is, one of the ways it will lose its potency is by diluting it, say in a large amount of water. As the salt dissolves and has more and more water added to it, it’s saltiness won’t be as strong. Or, salt that wasn’t properly cared for but exposed to things like moisture could have the same effect. Some scholars point out that pure salt technically doesn’t lose its saltiness in this process, so it’s probably not what Jesus has in mind.

What could Jesus have in mind, then? It turns out that the salt trade in Jesus’s time was open to just as much corruption as the other marketplace items, perhaps even more so since it was an expensive commodity. Imposter or impure salt, salt that had been mixed with other minerals or dirt, would bulk up the quantity while also dilute its quality—but without lowering its selling price.

Salt can be worth its weight in gold, especially because of its preservation properties. There are even historical references that describe certain kinds of salts being poured over embers of a fire at the end of the day, preserving the heat so that the next morning it would be easy to get a new fire going. Salt keeps the fire of life going!

Along with salt, Jesus describes the people listening as the light of the world, not meant to be hidden, but shining for others to see. No one, Jesus says, goes to the trouble and expense of lighting their lamp to then put it under a basket where its illuminating power is greatly diminished. Note that the lamp isn’t snuffed out, but more like contained and limited, not reaching its full potential or benefit.

These two images are meant to elucidate what Jesus is about to describe about fulfilling the law even as they bridge the gap between the Beatitudes and the law and the prophets. People who live through their current situations with the promises Jesus describes are living as lights in the darkness, letting the salt of God’s promises sustain and preserve them. Good works, what we do with our salt and light, is what the world will see.

According to Jesus, alongside the promises of God, God’s guidance on how to live also preserve and sustain God’s people. Keeping God’s law is the way we shine God’s glory and live as blessings for others. Jesus makes this point clear, emphasising that he came as the fulfillment of the law. I appreciate Donald Hagner’s commentary on this section of the Sermon on the Mount. Hagner argues that Jesus is describing himself as keeping every aspect—jot and tittle—of the law perfectly but having a grander vision than each individual law. Jesus fulfills the intention of the laws as a whole even as he keeps each law perfectly. Jesus is the pattern for saltiness and light as righteousness because he is the one who shows us God’s intention with the Torah.

This is a freeing word for us because we know that people during Jesus’s time accused him of sinning and associating with sinners. Even though it can be discerned in community, our measure of saltiness and brightness does not come from others alone but must also be guided and shaped by the Holy Spirit. In a sense, we take from the whole wisdom of Scripture to understand God’s ways of righteousness and we take from our own personal stories, contexts, and how God has knit us in our mother’s wombs to understand how we can be salt and light in the world. None of it is expendable—not our personalities, not God’s law.

How we integrate them as we follow Jesus will lead us on the journey of freedom that will exceed the demanding righteousness of the scribes and Pharisees, whose additional requirements and layers of law-keeping became its own bushel basket on the purposes of God.

Textual Point

Jesus moves from the future tense promises in the Beatitudes to present tense descriptions that match the ones that start each Beatitude. We are continuously living as salt and light in the world. The present tenseness of it reminds me of how we already play with this kind of language: people have salty (or spicy) personalities or they are described as “lighting up the room.” Some of us have even been told to tone things down a bit, and some of us have probably been told the same thing about our Christianity. Are we overcompensating to prove ourselves with our works, or are we living out of our true self?

Illustration Idea

My toddler has taken to copying me (or perhaps the way my husband pokes fun at me) by responding to us turning on the overhead lights, squinting with her hands over her eyes and saying, “Too bright.” I definitely do not enjoy overhead lights—just as I do not enjoy driving at night with LED headlights on the cars going in the opposite direction. I want our bedroom as dark as possible as I sleep and I will always prefer lamps to overhead fluorescent lights. For me, there is such a thing as too bright. Some of us use our Christian light and saltiness as a weapon rather than an illumination, or we enjoy making people uncomfortable, we are too bright and for the wrong reasons. It’s important that we don’t live our salt and light with ulterior motives.