Mark 9:38-50 (NRSV)
38 John said to him, "Teacher, we saw someone casting out demons in your name, and we tried to stop him, because he was not following us." 39 But Jesus said, "Do not stop him; for no one who does a deed of power in my name will be able soon afterward to speak evil of me. 40 Whoever is not against us is for us. 41 For truly I tell you, whoever gives you a cup of water to drink because you bear the name of Christ will by no means lose the reward. 42 "If any of you put a stumbling block before one of these little ones who believe in me, it would be better for you if a great millstone were hung around your neck and you were thrown into the sea. 43 If your hand causes you to stumble, cut it off; it is better for you to enter life maimed than to have two hands and to go to hell, to the unquenchable fire. 44 45 And if your foot causes you to stumble, cut it off; it is better for you to enter life lame than to have two feet and to be thrown into hell. 46 47 And if your eye causes you to stumble, tear it out; it is better for you to enter the kingdom of God with one eye than to have two eyes and to be thrown into hell, 48 where their worm never dies, and the fire is never quenched. 49 "For everyone will be salted with fire. 50 Salt is good; but if salt has lost its saltiness, how can you season it? Have salt in yourselves, and be at peace with one another."
Ruth Jacobs, who founded the Choristers Guild said,
You don't have to do great things, but little things you are doing can be done with great conviction, great wisdom, great beauty and great love.
Jesus was saying a similar thing when He said, "Have salt in yourselves . . . " In Jesus' day and for many centuries afterwards, salt was important as a preservative and healing agent. It also brought life and taste to food.
I also learned some years ago that salt was used as a fertilizer. It was mixed with the soil to help aerate and give acidity to the ground. During World War II, Europeans returned to using salt as a fertilizer when commercial fertilizers were unavailable. As followers of Jesus Christ, we are like fertilizer. Spread us in the soil and we make a difference.
Mike Metzger said,
Being salt and light demands two things: we practice purity in the midst of a fallen world and yet we lie in proximity to this fallen world. If you don't hold up both truths in tension, you invariable become useless and separated from the world God loves. For example, if you only practice purity apart from proximity to the culture, you inevitable become pietistic, separatist, and conceited. If you live in close proximity to the culture without also living in a holy manner, you become indistinguishable from fallen culture and useless in God's Kingdom.
Being salt as Jesus describes means making a positive impact on those around you. It means following Christ in such a way as to cause others to want to follow. Think about it.
Mike Metzger, Fine Tuning Tensions with Culture: The art of Being Salt and light (Suwannee, GA: Relevate, 2007), 4.