There was a problem in Jericho. The water was bad. So God told Elisha to take salt, a purifying agent, and sprinkle it on the root of the problem - the poisoned spring. God didn't mess with the fruit, the bad water, he made direct contact with the root. Today God wants to send His artists to the root of a poisoned area of society so it too can be purified from death and unfruitfulness.
Salt is also a preservative.
Before refrigeration existed, salt was rubbed into meat to keep it from spoiling - or being corrupted from bacteria. Our Christian influence works in a similar way. It restrains the corruption of the world, which if left unchecked, multiplies as quickly as bacteria on a hunk of meat. When America was young, the church actively used the most popular and available medium of the day - literature. Concerts and plays were popular too, but since they had to be seen in person it was a rare treat, especially for those living rurally.