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The Life of Jesus - Series 4: Episode 3

Disciples as salt and light

| Martin Charlesworth
Matthew 5:13-16
Luke 14:34-35
Mark 4:21-25

Jesus' disciples will be like salt - fertilising the good and disinfecting the bad in society. Christians offer the light of Jesus by their lives.

Jesus' disciples will be like salt - fertilising the good and disinfecting the bad in society. Christians offer the light of Jesus by their lives.


Hello and welcome to Series 4 and Episode 3. Our topic today is ‘Disciples as Salt and Light.’

Introduction and Recap

We are, in the Sermon on the Mount series, which is Series 4. We've moved from Series 3 where we spent a lot of time looking at the early ministry of Jesus (in and around Galilee, principally) which was a long series of exciting events: stories of healings, deliverance from evil, remarkable teaching, proclamation of God's Kingdom, huge crowds coming to Jesus and great popularity and great reputation. We also saw during that time a couple of other themes. One was the rising opposition of the religious authorities based in Jerusalem, who were beginning to investigate Jesus, beginning to question him and to be very concerned and to think that they're going to need to get rid of him because he's a threat to their establishment. . We've also seen the development of the gathering of disciples and that came to a conclusion just before the Sermon on the Mount when Jesus appointed the twelve Apostles.

In the Sermon on the Mount, we're looking at the character and lifestyle of Christian disciples. We've looked, so far, at Luke's teaching in Luke 6 on the Blessings and Woes: the blessings of true discipleship, despite all the suffering it may involve, and the woe or the trouble, or the suffering that will come on people who are only nominal Christians - Christians in name only but who don't live the lifestyle of Christian. In the last episode, we looked at the Beatitudes and spent time focusing on the fact that Jesus is very interested in character and inner attitudes. This is an important consideration because in many religious traditions what matters most is what you do - it's your outward actions. How moral are you? How religious are you? How good are your personal ethics, your family life, your sexual morality, your giving to the poor? All these types of things are considered very important but very rarely is the inner life and motivation looked at very closely. Jesus starts from the inside, rather than from the outside; he's looking at the heart and the formation of character. The Beatitudes are the formation of character, and so they are very appropriate to have at the beginning of the Sermon on the Mount: character first and actions will follow. Character comes from a changed heart; changed attitudes as the Holy Spirit works within us. I'm sure many of you will recognise this process going on in your Christian lives - whether you're mature Christians or whether you're new Christians, you'll recognise this. If you're looking at this series and you're not a believer in Jesus Christ, one of the things that I want to encourage you to think about is the fact that Jesus isn't just asking you to follow a set of rules and regulations; he's asking you to follow a new lifestyle that comes from changed attitudes within. We ended the study of the Beatitudes by my suggestion that you might want to focus on one of them and read it regularly, meditate on it, think about it maybe for a week or more, and ask the Holy Spirit to help you to develop a more appropriate attitude of heart in that particular area.

We now move on to a short teaching where Jesus uses two images (or metaphors, examples, or analogies) to explain what the function of Christians is supposed to be like in their society or in their community. He uses two very common examples of aspects of life in his culture to give us examples of the way that Christians should live. We're going to try and understand what these examples meant in his context, and then we're going to make some application to ourselves.

Matthew 5: 13 - 16 are quite well-known verses if you're familiar with the Bible; but I'm not sure the meaning is as well-known as the text, so we're going to really focus on understanding the meaning. Matthew 5: 13,

13 ‘“You are the salt of the earth. But if the salt loses its saltiness, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled underfoot. 14 “You are the light of the world. A town built on a hill cannot be hidden. 15 Neither do people light a lamp and put it under a bowl. Instead they put it on its stand, and it gives light to everyone in the house. 16 In the same way, let your light shine before others, that they may see your good deeds and glorify your Father in heaven.”’

Matthew 5:13-16, NIV

Let's look at the first image that Jesus uses, the image of salt, and he says to his disciples, “You're the salt of the earth,” by which he means the land, the earth, the farming land - “You're like salt on the land.” I wonder what this could mean? Christians generally have understood this passage to refer to the function of being a preservative, a bit like the function of salt in food - where if you haven't got refrigeration it preserves it for longer from going off and being inedible. It's interesting that Jesus says, “You are the salt of the earth,” of the land.

We're going to think what that could have meant to his contemporaries. The first thing to say is that salt was a very readily available commodity in ancient Israel, for a very simple reason - that there was a natural formation of salt in their area and in their environment. This came about through a unique feature on the eastern side of the country. The River Jordan runs down the eastern side of the land of Israel from the north, where there are hills in Lebanon and Mount Herman and elsewhere. This leads to water coming down into Galilee and forming the Sea of Galilee, the freshwater lake by which Jesus lived at Capernaum and on which he sailed on many occasions. The River Jordan then leaves the Sea of Galilee and goes south and it enters into what we call the Dead Sea, which doesn't have any exit. This is stagnant, static water that doesn't drain off anywhere and the Dead Sea is dead because it's filled with salt. It has a hugely high salt percentage in the water, nothing lives in that water, and salt deposits appear on the land around the Dead Sea. Modern tourists frequently travel to the Dead Sea for the simple novelty of the fact that you can float on the water - you don't sink because of the amount of salt in the strange composition of the water. Salt was readily available, you could even find it at salt deposits on the land in different places near the Dead Sea.

That's the first thing to think about: a readily available commodity. But what was salt actually used for? Luke has another version of this saying that describes two particular functions of salt in their society and I think we should take our clue from what Luke says. I'm going to read from Luke 14, verses 34 and 35, where Jesus is commenting on the power of salt and using it as an analogy. Luke 14: 34 and 35:

‘“34Salt is good, but if it loses its saltiness, how can it be made salty again? 35It is fit neither for the soil nor ... the manure pile; it is thrown out.”’

Luke 14:34-35, NIV

This is interesting because Jesus specifically describes the function of salt - and it's not a preservative in food - this is to do with the land. He says, ‘“If salt loses its saltiness,”’ in other words, if it loses its appropriate chemical composition - if other things are added in - (which frequently happened with salt deposits from the Dead Sea, by the way) then it's fit neither for the soil nor the manure pile. What was salt used for on the soil? It was used as a fertiliser. Salt, in small quantities, is a good fertiliser. In fact, modern chemical fertilisers have significant salt within them and, before they were invented in the Western world, salt was used in agriculture as one of several natural fertilisers and has been done throughout the ages in different societies. Salt here is pictured as a fertiliser.

Secondly, it is pictured as fit for the manure pile - the animal excrement or the human excrement - and salt was applied to manure in order to disinfect it and prevent disease or infection spreading from it. This was obviously a common use of salt at the time. We have two functions that Jesus defines here in this short passage in Luke 14 where he's describing the same metaphor or image that we have in the Sermon on the Mount and these two things are fertilising and disinfecting.

Let's reflect on this because this is the core of the meaning: fertilising the good and disinfecting the bad. This is a good way of describing the functions of Christians in society. There are many good things in your society and mine, many things that work well, many things that are beneficial to that society. They'll vary from one country to another, from one region of the world to another. They might be to do with administration or financial structures or healthcare or educational provision; there might be some really good things or some cultural values of care for the poor or the elderly or children - there's all sorts of good things that could be in your society. It might be to do with particular technology that your society has which is very beneficial to people. Jesus is, basically, saying that the function of Christians is to encourage the good as well as to discourage the bad because, just as I could say there are many good things in your society, I could also say there are many bad things in your society and also in mine. We have lots of technology, lots of commitment to education and welfare and medicine in my society, but we also have lots of bad things: the breakdown of the family, violence and discrimination against people and all sorts of other things too. Some things are good and some things are less good in our society and Jesus' point is that Christians will make a contribution to encourage the good and to discourage the bad. If there's going to be violence or sectarianism, we would be seeking to be peacemakers; if there's going to be financial corruption, Christians would be those who would use their influence to resist that. If there are good things that need to be encouraged like, for example, education. Christians are often at the forefront of education because it develops people, it encourages people, it gives them opportunities. Christian discipleship will have two significant benefits for any society: if Christians are mature and practical and functioning in their faith effectively they will encourage good things and they will discourage negative things that could undermine that society. You can think of some applications in your society. Obviously we are thinking about societies and cultures all the way across the world that are very different from each other. You can think of some applications for you which might be very different from the applications that I would make for myself in my own country - that doesn't matter, that's good! The Gospel works in many different cultures but it has the same positive effects as Christians are true disciples and take their responsibilities in their society seriously. I'd encourage you to see that as a significant part of what you can contribute in your society. You may think, “I have very little influence.” Well, use the influence you have with just a few people, with your family, with your friends, in your workplace, with the prayers you pray for people, with your attitude towards people and with your witness to Christ.


The second image or metaphor that Jesus uses here is that of light:

14You are the light of the world. A town built on a hill cannot be hidden. 15 Neither do people light a lamp and put it under a bowl. Instead they put it on its stand, and it gives light to everyone in the house.”’

Matthew 5:14-15, NIV

Lighting in those days came by candles or by oil lamps - this is long before electricity of course - and those candles and oil lamps were very important. Jesus says that a town or 'a city built on a hill cannot be hidden'. That's very true and Jerusalem is one of those towns or cities. The city of Jerusalem was built on a hill and was visible from some distance away, a good example of that saying. A lamp is put on a stand when it's in a house. Houses in those days, very often, had one main room and the main room was the one which would be lit up in the evening, if you were short of candles or oil lamps people would gather in the main room. It's very important that the light is as prominent as possible, raise it up, put it on the table, put it on a stand, make sure the light goes as far as it can because there's very little light and we have very little resources in that kind of society for lighting.

This is the analogy that Jesus uses: Christians light up the room, Christians provide light in society. How do they do that? By their moral integrity and by their saving message. It's the character of Christians that brings light to people, as it were, and it's the message that Christians bring that brings light to them. Just as we are called to be the light of the world, so in a very specific sense, according to John, Jesus is ‘the light of the world.’ John 8: 12,

‘When Jesus spoke again to the people, he said, “I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life.”’

John 8:12, NIV

That's a passage we're going to study later on in this study of the life of Jesus. “I am the light of the world, you are the light of the world.” Isaiah 49: 6, describes the Servant of the Lord, which is Jesus, prophetically as being ‘a light for the Gentiles,’ a light for all the nations of the world, and so the life of Christians is supposed to bring light into dark places - that's the point of what Jesus is saying, We can easily underestimate the significance of Christians and their life. We are, potentially, very influential to people around us. We bring insight, that's what light does, you can see things more clearly; we bring perspective; we bring truth, as we bring the Gospel truth or some ethical or moral truth to people, and that provides light for people around us. This, of course, only happens if Christians are living a life of integrity themselves and this is what the Sermon on the Mount is about. Some examples of what integrity means are to be studied very shortly - they're in the passages that follow after this one where Jesus very specifically describes the character and the lifestyle of Christians with respect to a number of particular moral issues, and if you connect that with this saying, as we live out those moral principles, then we provide examples for people around which should enlighten them, should encourage them to follow suit and perhaps even to follow the Jesus who we serve as his disciples.

These are very short, pithy statements - ‘“You are the salt of the earth. You are the light of the world”’ - and we might think, “Goodness me! I don't feel like that. I feel very insignificant. I feel very unqualified. I don't feel my life is fully in order yet.” Those are reasonable things to feel, but I want to encourage you to see these sayings as part of this wider Sermon on the Mount and, when you've come to the end of the Sermon on the Mount (and maybe you've made some changes in your life as a result of it and you're more committed to that process of discipleship) then you can come back to these sayings and say with a little bit more confidence, “Yes, I am supposed to be salt on this earth. I am supposed to be light in this world.”


As we bring this study to an end, I want to bring some final reflections and learning points. There is a real risk that Christians can lose their impact on the world if they compromise on discipleship. We need to get away from the idea that Christianity is like joining a club or just joining a family, or getting a ticket to heaven or a ticket to a comfortable life. You may never have thought any of those things but they're popular ideas. In the Western world, for example, we're very influenced by a philosophy you might call individualism: that every individual has a right to happiness and they need to find their happiness in whatever way suits them, as long as they don't harm other people. That's the way a lot of people think and, if you take that idea and you put it into Christian life, the idea becomes that you get out of Christianity what you want, to make yourself comfortable and happy. Jesus speaks in a completely opposite manner. He says to us, “I've redeemed you. I've called you to follow me. You're sinners. I've forgiven you, given you eternal life, given you the Holy Spirit. Now come follow me. Serve me, serve my Kingdom, extend my Kingdom.” Therefore, change your life to become an active disciple, giving attention to all the details of your life and then you'll be influential. There is a risk of losing impact if we compromise on discipleship, which is why the Sermon on the Mount is such a very important part of the Gospels and the New Testament and should be central in our studies if we are seriously seeking to follow Jesus Christ.

Salt speaks, primarily, of our moral influence in society and light speaks, primarily, of pointing to Jesus Christ. We are actually pointing to the greater Light of the World because (as we read in John 8: 12) Jesus himself, ultimately, is that light. We are signposts to Jesus by witnessing to him and sharing our faith in him.

In conclusion, we need to go to verse 16 which is a great encouragement. Matthew 5: 16, just to read it again:

‘“In the same way, let your light shine before others, (so) that they may see your good deeds and glorify your Father in heaven.”’

Matthew 5:16, NIV

Here we see an interesting pattern that Jesus identifies: many people are drawn to Christ and faith through the good deeds, or the good lives of Christians. The example of Christian faith lived out individually, in family and in community, influences people and draws them to active faith, enabling us to witness to them. This has been the pattern all the way throughout Church history: people are drawn by the good witness of Christians and Jesus predicts that some of them “will glorify your Father in heaven” - they can only do that by having active belief in Jesus Christ and being born-again and coming into the Kingdom of God themselves. I want to encourage you with that thought: our lifestyle, our good deeds, our integrity, have more of an influence on other people than you realise. Very often, they watch you a lot and might say very little until, one day, the story comes out and they've noticed the way that you have lived. That's certainly happened to me with people who've become believers after observing carefully to see, “Is there integrity here?” I encourage you, let there be integrity throughout your life, let the Sermon on the Mount be a living reality for you and I invite you to join with us as we continue this study in the next episode.

Study Questions

The following questions have been provided to facilitate discussion or further reflection. Please feel free to answer any, or all the questions. Each question has been assigned a category to help guide you.

  • Exploring Faith
    Exploring Faith
    1. In what ways can church seem to be just another ‘club’? What is Jesus calling us to?
  • Discipleship
    1. In the light of this study, explain what it means to be salt and light in your community.
  • Further Study
    Further Study
    1. Discuss what could be the effect on witness when discipleship is compromised?
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