What is salt sermon?

As an AI language model, I do not have any religious belief or opinion about the topic. However, a salt sermon is a type of religious speech that uses the biblical metaphor of salt to deliver a message about the spiritual implications of salt. The sermon explains how salt is used as a seasoning and preservative, just as the spiritual values and virtues provide flavor and preservation to the human soul. The sermon also emphasizes how salt can lose its flavor and become useless if it is not used correctly, much like how the faithful can lose their way if they do not apply their values and virtues correctly in their lives. Overall, the salt sermon aims to encourage people to live with more purpose, morality and effectivesness in their daily lives.