When Jesus said to his disciples “You are the salt of the earth and the light of the world” it would have been crystal clear what he meant to a first century Jew, but to us it is little more than a nice thing to say. We might as well say “you are pepper in the mill” or “chlorine in the water” or “Coke in the bottle”. We know what salt is used for and pepper, chlorine and coke have similar uses: stopping meat from going bad; making food tasty; developing a thirst. All these find parallels in the Christian life; preserving society by stopping the rot; making others thirst for God; giving flavour to the world. We know too that light dispels the darkness of evil but in Matthew 5:13-16 Jesus says nothing about how his disciples are to do this. We need to look to the wider context to know what Jesus means by salt and light or else just make up what this means for ourselves.
The first context for these descriptions of what Jesus’ disciples are is of course the sermon on the mount itself. The second and wider context is the Hebrew scriptures, through which any first century Jew would have known exactly what Jesus meant for him to be salt and light.
In the sermon on the mount, Matthew 5:13-16 falls just after the beatitudes and before Jesus’ teaching on the law. This section of the sermon is like a hinge, holding the door to the post, it links two pieces of Jesus’ teaching. In this context, to be salt and light is to have strict obedience to the law but with the humble character of the beatitudes. Salt is one half of the life of the disciple and light the other half. They are not the same thing.
This reading is supported by the wider context of the Hebrew scriptures. Salt was widely used in the sacrificial system as a means of purifying the sacrifice. This explains the phrase Jesus uses in Mark 9, “you will be salted with fire” which Paul puts as “offer your lives as a living sacrifice, holy and pleasing.” Salt was also used to seal covenants and the two uses come together in Leviticus 2:13:
Season all your grain offerings with salt. Do not leave the salt of the covenant of your God out of your grain offerings; add salt to all your offerings.
(See also Numbers 18:19; 2 Chron 13:5-6)
This image of saltiness explains why the impure, covenant breaker who has lost his saltiness might be thrown out and trampled underfoot (Matthew 5:13).
What then is the Hebrew context for light? Much Hebrew poetry uses light in the context of beatitude. David’s song in 2 Samuel 22:26-29 sets light in the context of the greatness of God and the weakness of man:
“To the faithful you show yourself faithful, to the blameless you show yourself blameless, to the pure you show yourself pure, but to the crooked you show yourself shrewd. You save the humble, but your eyes are on the haughty to bring them low. You are my lamp, O LORD; the LORD turns my darkness into light.” (2 Samuel 22:26-29)
(See also Psalm 27:1, 36:9, 56:10-13, 89:15-17, Prov 13:9, Isa 2:5, 9:2-3, Isa 42:6-7 and Micah 7:8-9.)
Light is what God shines into the darkness (Gen 1:3) and in his light we see light. Without God we are in the dark, this is the language of the beatitudes.
And so, to be the power of God in the world, the disciples of Christ need strict obedience to the terms of the covenant, the law of God and the character of one humbled, brought low, poor in spirit, meek and pure.
There is a constant tug of war in the disciple’s life between the two. Sometimes tending to legalistic piety, pride and finger wagging hypocrisy at other times tending to meekness and mercy whilst sinning with impunity, thus risking being thrown out and being trampled underfoot. The believer in this situation will return to the cross and begin the process of the beatitudes all over again. We do this by coming back, again and again, to the cross.
This tug of war does not only exist in the life of the individual but also in the church and most clearly in the life of the Anglican Church. The tearing and dislocation of the church has been caused by those who are heard to be big on being salt, obedient to the law, on one side and those who are heard and seen to be big on mercy and meekness but who have given up on the law. The power of the gospel of Christ will only been seen when the two camps stop pulling apart and instead all pull together by strict obedience to the law of God combined with the greatest meekness and mercy.