Stop the Rot!

Sermon on Matthew 5:13-20, Preached at St Paul's, Ashgrove for the Fifth Sunday After Epiphany

Feb 06, 2026

I remember hearing a sermon on this Gospel passage when I was a kid, and an illustration from it has stuck in my mind for reasons that will become obvious. It went a bit like this:

Last night I arrived home from work, and I was really hungry and looking forward to the sausages and mashed potatoes that I could smell cooking. I sat at the table and the food on my plate looked so good! Then I tasted it. It was so awful I couldn’t eat it. My wife had forgotten to put salt in the mashed potatoes!

He then went on to talk about how we can’t live without salt.

The reason I remember it is because I felt some strong emotions as I listened. I was young but I knew it was not OK for preachers to use their platform to criticise their spouse. But the reason it keeps coming to mind is that it seems so strange now that anyone would put salt in mashed potatoes – let alone find them inedible without salt.

Our eating habits have changed so much from my childhood in a small country town where sausages and mashed potatoes – with lots of salt - made an almost daily appearance on our dinner tables. Since then, the health impacts of excessive salt intake have become generally known, and most of us have considerably cut back on the amount of salt we add to our food.

Those changes have happened just over my lifetime. Over the past 2,000 years, human use of salt has changed even more. That means that if we are going to understand what Jesus meant about his disciples being the salt of the earth, it is probably not going to be very helpful to look at how we use salt today. And I’m pretty sure Jesus wasn’t talking about mashed potatoes at all.

He wasn’t talking about changing the way food tastes. He wasn’t saying the church should add flavour to the world. He wasn’t saying that Christians should use their influence to make bland experiences more palatable. He wasn’t saying that believing in Heaven makes life here more endurable.

To understand what he was saying, we need to think back to a world before refrigeration – many centuries before refrigeration. How can food be stored in a hot climate when you can’t put it in the fridge? Frankly, I’m no expert, but I understand enough to know that it comes down to salt and sunlight. Food could be salted to stop it from going bad, or it could be dried in the sun. Salt and light stop food from going bad and allow it to be stored for longer.

So, when Jesus told his disciples that they are the salt of the earth, he wasn’t saying they should make life more palatable for the people around them. He was saying they should stop their world from going bad: that they should stop the rot, as it were, in their communities.

That’s a big ask, isn’t it! This little bunch of eager but somewhat inept followers of Jesus is supposed to stop their world from going bad. That’s an overwhelming task, but Jesus goes on to explain that what matters is not the size of their influence but the quality of their lives as a community.

In a world that is headed in the direction of corruption and decay…

in a world where people with wealth and power are accumulating more and more wealth and power, without scrutiny, at the expense of people who have little and are in danger is losing what they have…

in a world where some people – like the Herod dynasty for example - are using religion to justify their tyranny…

Jesus calls his followers to be a bubble of healthy hope where people act with integrity and respect, even when it costs them.

These chapters, called the Sermon on the Mount, are like a constitution for the church – or a charter or a values statement. They are an ambitious statement that is always aspirational. We have never seen the church living this out perfectly or consistently, but this is what we are aiming for, and when the church gets close to this, we can be a preservative for a society that is going bad.

The opposite is also true, as Jesus says: if salt loses its saltiness – if the church takes on the same values and aspirations as the society around it - then the church, like the salt, becomes useless. In fact, if we look at the history of the church, we find lots of times when the church has been very salty: when groups of Christians have helped their societies to change for the better. It was Christians, like the Quakers in the US and William Wilberforce in the UK, who fought against slavery until it was eventually made illegal.

Of course, we also know of times when churches have given spurious justification to brutal regimes and empowered them to become even more brutal. When the church has lost its saltiness, it doesn’t just become ineffective – it does harm. But when the church has been salty, it has sometimes stopped the rot and reversed the tide of evil.

This is what the Sermon on the Mount is all about, and it is central – constitutive – to our identity, so it is a bit unfortunate that the lectionary only gives us one Sunday on it this year. Because of that I’m going to give you a quick summary of the areas it covers.

5:21-26 ~ The church is to be a community where people manage their anger well. You have laws against murder, Jesus says, and that’s great, but you need to do better than that. Not just “no murder”, but “no verbal abuse”. No insults. In your community you must do nothing intended to harm another person. And if you realise you have harmed someone, then you immediately go and apologise. There is nothing more important than maintaining good relationships in the church.

We live in a world that is finding conflict harder and harder to manage well. It is hard for us too. So, we need to keep working on it.

5:27-33 ~ This part is hard to talk about and to hear. Treating people with respect is especially important in relationships where sexual attraction might be a factor. Jesus is starkly insistent that among us no person is to be used as a plaything – even in the mind; even in the eyes. Every person is to be treated with honour and respect, and marriage vows are to be valued, because marriage partners are to be valued.

There was another drop of Epstein files last week, so we are all aware of the damage that has been done when vulnerable children are sold as playthings. We may also be aware that a lack of online regulation has facilitated previously unimaginable abuses of vulnerable children1 and that AI tools have allowed innocent photos to be rendered pornographic.

We might feel powerless against this sort of evil. There are things everyone can do, though. There are organisations we can support, like International Justice Mission. And Jesus says that the most powerful and fundamental thing we can do is to ensure that in the church, in each of our relationships, there is nothing but the highest level of respect.

5:33-37 ~ Jesus tells his followers to think carefully before making vows because if you are consistently honest, vows shouldn’t be necessary. People should be able to trust you so completely that your yes or no is sufficient.

Between politicians who strategically “flood the zone with BS” to deep fake AI videos, we have seen way too much evidence of the damage that dishonesty does to the world – the putrification that can set in when a society is not honest.

5:38-48 ~ People sometimes go along with the rot because they fear they will be hurt if they live in a different direction from the people around them. And Jesus is realistic about that. He says, yes, you do need to prepare for that possibility. And his instruction is: don’t make things worse by retaliating. Meeting violence with violence only makes the world more violent.

That doesn’t mean allowing abuse to continue, because Jesus calls us to love our enemies, and the most loving thing we can do for a violent person is to prevent them from exercising further violence.

6:1-18 ~ Jesus then turns his attention to a religious sort of rot where people perform their religion publicly in order to get something for themselves. If you have read a lot of history, you will know how much damage has been done in the past by people who use religion to make themselves and their friends powerful. And if you stay on top of the news, you will know how much damage this is doing today.

Religious practice – prayer, fasting, giving to charity - is all great, Jesus says, but make sure no-one sees you do it, especially if there is any chance you might be rewarded for it.

6:19-34 ~ If you live by the Sermon on the Mount, it will not make you rich. Living against the current of the world never does. So, we need to think carefully about this. We need to see the world clearly – see the rot and choose to be the salt that stops it. That will mean valuing God’s kingdom so highly that we choose to invest there, and serve God rather than wealth, trusting God to supply what we really need.

7:1-29 ~ All this is so difficult that we are all bound to fall short sometimes, so we must practice being gentle with ourselves and with each other. We don’t judge each other when we fail, but we do try to be discerning. We need to be clear eyed enough to see the rot and always, always remember that the rot we are called to combat is never a person or a group of people. It is the system that tends to channel human behaviour in harmful directions.

This might feel a bit legalistic when we look at it all at once, but Jesus isn’t telling us to do these things to make God love us or to get us into Heaven. He is calling us to be salt and light in our world for the sake of our world – to bring vitality and flourishing to the communities around us. That’s why Jesus tells his followers to embody righteousness that exceeds that of the religious leaders of his time – not because God’s standards are higher but because our world needs more: more salt and more light.

This is about the sort of behaviour that makes a community worth living in. There are things we can do to actively move our communities in healthy directions, but the main focus is to practice these behaviours among ourselves and with our neighbours – so, regardless of how small and under-resourced and powerless we feel, we can be a little bubble of light, an enclave of integrity, a salty preservative to bring vitality to just a little bit of our world.

With Love from Rev Margaret

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