Jesus' mission is to invade and retake the world...redeeming it and re-establishing His rule and Kingdom.  He is doing that through some very unlikely people.  He gives them the honorable titles of being both "Salt" and "Light" of the world. Then He warns them not to lose their saltiness or to hide their light.

Psalm 112

Matthew 5:1-16

Colossians 4:5-6

Psalm 112:6-8

God makes a call to all of us, whether grand or small.

1 Samuel 3:1-10