The great theme of Jesus’ public ministry was the kingdom of God. In Jesus, God was intervening in history decisively so as to recover his purposes for his entire creation and to lead it towards the destiny he always intended for it. Not surprisingly, therefore, the kingdom of God is also the theme of Jesus’ longest recorded sermon, the Sermon on the Mount (Matthew 5-7). 

Jesus begins his remarkable sermon with the characteristics of the citizens of his kingdom, the beatitudes. Reading them today one is struck again by just how radical and countercultural they are. What is not always noticed is that they are also a picture of the king of the kingdom, namely Jesus. When we enter his kingdom, the Spirit works in our lives to make us like him. 

Jesus’ influence on history is incalculable, and thus, once he has set out the character of his followers, he explains in Matt 5:13-16 the influence they will have on the world. To evoke this, Jesus reaches for two metaphors, one from the kitchen – salt – and one from the sky – light. Every kitchen has humble salt on its shelves. As today, salt flavoured food but in a world without electricity it also functioned as a preservative, rubbed into meat to prevent it from going off. Although salt has the positive element of flavouring to it, its primary connotation is negative. Societies have a habit of going bad, and Christians are to be rubbed deeply into their societies to hold back decay and to keep them healthy. As John Stott writes, “God intends us to penetrate the world. Christian salt has no business to remain snugly in elegant little ecclesiastical salt cellars; our place is to be rubbed into the secular community, as salt is rubbed into meat, to stop it going bad.” (1)

Light, on the other hand, is a wonderfully positive metaphor. God is light, Jesus is the light of the world, and Christians are to be lamps shining the Christ light into the world and dispelling its darkness. The German theologian and martyr, Dietrich Bonhoeffer, would say that we have to keep reminding the world, that world which causes us so much pain, that it is indeed the world, i.e. God’s good creation. Through word and deed Christians are called to show people that the world is God’s creation, that despite our rebellion he holds it in existence, and that he longs to forgive us and to welcome us into his kingdom, and to show us what fully human life is like both personally and societally. 

One simply cannot read Matt 5:13-16 and think that Christians should have nothing to do with society, with politics, economics, education, art, leisure, medicine, agriculture, poetry, international relations, etc. The good news of Jesus is good news for all of life and we are called to incarnate this news in every aspect of our lives. In the West, modernity has dealt with religion by privatising it, reducing it to a leisure activity and preventing it from engaging the great public spheres of life. Alas, far too many Christians have gone along with this, being good church people but following the world in the public spheres of life. In so many ways Evangelicals have struggled to recover this salt and light mission taught so clearly by Jesus. Some have responded to modernity by reducing the mission of the church to evangelism. Evangelism is utterly central to the mission of the church. John Stott was himself a truly great evangelist. I met him when he came to speak for a university mission at Oxford, and his talks were outstanding. But, what value is word if it is not accompanied by deed, by a way of living in all areas of life that makes our words inherently plausible? 

I regard John Stott as one of the great ones of the twentieth century. But, he did not come to this salt and light vision overnight. One can track Stott’s growing understanding of the comprehensive mission of the church to his mature vision embodied in the Lausanne Covenant of 1974 and in his Christian Mission in the Modern World. This was followed by his growing emphasis on ethical apologetics and his seminal book, Issues Facing Christians Today. 

Once we recover this holistic salt and light vision, a critical question becomes how we are to be salt and light today. Certainly, we must continue to privilege evangelism, but how are we to engage politics and economics, education and sexuality, etc.? These questions require close and deep attention and that is precisely what public theology and the KLC are all about. For now, an important caveat. Jesus warns us that if we lose our saltiness we are no longer of any use. 

How might this happen? It is when we cease to embody the beatitudes, when we cease to be like Jesus, that we lose our restraining and positive influence on society. This moves spiritual formation front and centre. Unless we are being formed by the Spirit to become more and more like Jesus, embodying ever more fully the virtues of the beatitudes, we will tragically contribute to the decay and darkness in our cultures. Matt 5-7 contains lots of ethical teaching but right at its centre is … the Lord’s Prayer. Prayer flows, of course, from being poor in spirit, and it is the one thing necessary for being salt and light. Herman Bavinck as a theologian, and John Stott as a pastor-organic intellectual, both rightly emphasised that ultimately our life and work is all about the glory of God (Matt 5:16). If we are to enhance God’s reputation in his world, then nothing is more important than living ever more deeply into the very life of God, being shaped and formed by the Spirit to be like Jesus.