"You are the salt of the earth. . . . " - Matthew 5:13
In the ancient world, salt was used as a preservative. It still is today-ham, corned beef, olives, pickles, and even anchovies are preserved in brine, a saltwater solution. The purpose of the salt is to stop the food from spoiling, to prevent its corruption.
Now when Jesus says we are to be salt, it means that you and I, as Christians, should seek to be a preservative wherever we are.
For example, if you are a parent, you can guide your children in what they watch on TV and in what they read. You can teach them Christian values, and live as an example to them.
If you are the only Christian in your family, then you are probably always the one who is asked to give the blessing over the Thanksgiving meal. That is good, because it means they notice that you are a Christian.
You also need to be salt in the place where you work. You can refuse to gossip about coworkers, you can do your work without grumbling, and you can be an encouragement to others.
Maybe a bunch of the guys are getting together and telling a joke, but when you walk in, everyone falls silent all of a sudden. Why is that? Because they know you are a representative of Jesus. You are functioning as a preservative in that situation.
Or maybe you are that one Christian student in your classroom. You need to stand up for Christian values. You can refuse to participate in harmful activities and tell your friends why.
Now that is being salt. I didn't say it would make you popular. I said you are being salt. It's hard at times. But you need to do it.
As you let the Holy Spirit help you and guide you, you can be a good, salty preservative for those around you.