I don't understand my daily verse, Matthew 5:13. Can you explain it?
Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.
In that verse, Jesus is comparing Christians to salt. Before refrigerators, salt was one of the main means of preserving foods. By comparing us to salt, Jesus was calling us the preserving influence in a decaying world. Because of sin, the world we live in is rotting spiritually. Today, the more wicked the sin, the more fashionable it seems. While it doesn't make us popular with the world, Christians are to live differently from the world and take a public stand against sin. By doing so, we slow down the whole-sale acceptance of sin--in effect, slowing down the rotting process.
Salt also has the characteristic of making one thirsty. When others see what God can do in our lives, it makes them thirsty for Christ. While our lifestyle is not to be the only witness we give, it is one of the most effective and demonstrative witnesses. When the world sees how Christ changed our wretched souls, they will want what we have.
And last, salt is necessary for physically well being. A preacher I know was told to cut down on his salt intake. He decided to stop eating salt altogether and experienced all kinds of physical and emotional problems. Just as the body needs salt, the world needs to see what Christ can do in a human life. Without us, they will surely perish.
Of course, if salt gets wet or otherwise ruined, it does none of these things. It has no purpose and is discarded. A Christian who is not living like God commands has no purpose either. He or she becomes spiritually "good for nothing." That doesn't mean that Christ will disown them. They are still Christ's; but they are useless to Him. Other Scriptures teach us that Christ will discipline these kinds of Christians and if they will not heed His correction, He may ultimately take them to heaven early (1Corinthans 5:1-5, 11:30).
I hope this gives you some understanding of the verse.