Summary: True Christians cannot remain secret for long.
SALT AND LIGHT
The metaphors of salt and light follow immediately after Jesus’ profile of the blessed Christian. The meek shall inherit the earth (Matthew 5:5) because meekness is not weakness, but quite the contrary. The peacemakers (Matthew 5:9) are surely not merely sitting at home in their closets contemplating God?
Even the threat of persecution (Matthew 5:10-11) should never drive the church so far underground that we are no longer communicating the gospel through our life and attitudes towards those around us: rather we are to be set on a hill (Matthew 5:14). We are not of this world, but we have a role to play until such time as the Lord sees fit to take us out of here (John 17:15-16). We are to shun evil, but we were never meant to be so heavenly minded as to be of no earthly use, as the saying goes.
Salt (Matthew 5:13) is a very useful commodity. Trade is built upon it; wars have been fought over it; taxes upon it have been resisted. Films have even been made about it.
Its uses range from being a condiment to being a preservative. At one time no house could do without it. As Christianity has spread throughout the earth there has been more than God’s common grace preserving the world from utter moral and spiritual decay.
Pure salt is not necessarily capable of decay, but it loses its savour when mixed with that which is not salt. Other white powders exist on the coasts of the Dead Sea, which may be mistaken for salt. And if the mixture becomes wet, it is the real salt which is dissolved.
If we allow an admixture of non-Christian principles to permeate our lives, then our effective saltiness is lost. The residue of that which has lost its saltiness makes for a good footpath, but little else. The Christian who compromises his testimony loses the respect even of those who used to persecute him.
Light (Matthew 5:14) is also an essential commodity. If you have ever been travelling through the countryside to a town or city, and seen the distant lights of your destination seeming to draw ever closer, then that is the picture which we have here. If the city is built on a hill, then you will not miss it, though you might quite fail to find a small village nestling in a hidden valley.
Likewise in our homes (Matthew 5:15), we tend to have a source of illumination in every room. We don’t keep our reading lamps under a rhubarb bucket in the porch (if we have such a thing). Electric lamps are most likely to be on the ceiling, where their light can disseminate throughout the room.
There have been secret Christians - like Nicodemus, and Joseph of Arimathea, in Jesus’ own time - but by and by they must reveal themselves and nail their colours clearly to the mast (John 19:38-42). Jesus is the light of the world (John 8:12; John 9:5), but we have also been commissioned to bear His light to the nations (Acts 13:47). This is done through evangelism, but also through living the life of Christ before men (Matthew 5:16).
Jesus warns us against making a show of our piety before men, in order to be seen of them (Matthew 6:1). This is in order to redress a propensity for theatrical display which gratifies itself with the applause of men. Jesus encourages us to do our works of piety for the glory of God, without drawing attention to ourselves.