You are the salt of the earth; but if the salt loses its flavor, how shall it be seasoned? It is then good for nothing but to be thrown out and trampled underfoot by men. (Matthew 5:13)
You Christian, must be an influence of righteousness in a world of sin and death. Your words and actions must stimulate those around you to greater, better things for God. That is why you must guard yourself from sin, for it will destroy your good influence. As contaminated salt loses its usefulness for flavoring food and so was cast onto the foot trails (lest it destroy fertile soil), the Christian who loses his godly influence becomes ineffective, even destructive, to the cause of Christ. Protect your influence as you follow Christ, and season the world with goodness and holiness.