If you are loving God more than anyone or anything else, if you are taking up the cross and following Jesus, then you are going to make a difference. You will impact your culture. The first-century church turned their world upside down because they lived this way.
It is also why the 21st-century church is not turning our world upside down, because, frankly, not enough people are living this way. We have fair-weather followers, but we have very few disciples.
Jesus said, "Salt is good for seasoning. But if it loses its flavor, how do you make it salty again? Flavorless salt is good neither for the soil nor for the manure pile. It is thrown away . . . " (Luke 14:34–35). What good is salt that isn't salty? And what good is a Christian who doesn't live as a Christian, a Christian who wants to just blend in and never speak out about what is true?
Salt in the first century was something more than a mere seasoning. Back then, salt was a valuable commodity—so valuable, in fact, that the Romans would sometimes be paid in salt. Hence the expression, "He is not worth his salt." When Jesus said, "You are the salt of the earth" (Matthew 5:13), He was saying, "You are valuable. You can make a difference."
A little bit of salt can change something. It can enhance the flavor. And just as salt makes a difference, one Christian in a dark situation also can make a difference. Salt stimulates thirst as well. Christians who are living their lives the way they ought to will stimulate in others a thirst for Jesus Christ.
Salt is valuable. Salt makes a difference. Salt stimulates thirst. So be a salty Christian. Be a representative of Jesus Christ in this culture.