Christians are called to stimulate the growth of truth and righteousness - to increase the production of goodness in the world. The church, the body of Christ, is the salt - the dungheap, the compost pile, the manure that must find its way into and fertilize the barren soil of lonely, hopeless souls.
Like a pinch of leaven in the dough; like a sprinkle of salt or a shovelful of manure in the flowerbed; or even like a single simple construction worker's son wandering within a tiny, primitive country, God has always had a way of making a little go a long way.
Salt is a doubly descriptive image of this principle at work. As well as being a kind of soul-enriching fertilizer, salt also makes us thirsty. Airplanes and bars know that by putting out free snacks like salty peanuts and pretzels they will increase patrons' thirst and thus their drink sales. In the same way the church as salt should stimulate the thirst of others for the good things of God, for the amazing things of the Spirit.