Matthew 5:13 You are the salt of the earth. But if the salt loses its saltiness, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled by men.
There are two communities of people in the world. They comprise the Church and the Lost. The two communities are different and on opposing ends of the spectrum. The Lost exist in darkness created by their own sinful preferences and rejection of God. This sinfulness not only darkens or blinds the world from the truth but causes it to self-destruct or decay as it begins to feed upon itself.
The Church in opposing fashion brings flavor and light to the world by the truth it reveals from God. The works performed by Christians acting in faith, will bring the truth of God to the eyes of the world.
As salt we are to preserve in the world Christian moral and ethical standards: God's standards. We are to inhibit the decay in society wherever we are able to make contact. Our daily lives are to be used to this end. Our saltiness must remain pure. We cannot take a compromising approach to our Christianity. To mix the world's views with our Christian faith will cause us to lose our effectiveness in our evangelical mission.