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. And when society does go bad, we Christians tend to throw up our hands in pious horror and reproach the non-Christian world; but should we not rather reproach ourselves? One can hardly blame unsalted meat for going bad. It cannot do anything else. The real question to ask is: Where is the salt?
John Stott in The Message of the Sermon on the Mount, p 65.