We are the people of God, as the Bible itself describes: Holy nation, royal priesthood, people acquired by God. We are owned by God, we belong to Him and no one else. He is our owner and Lord, and therefore it is important that we know those things that the Bible tells us we are, so that we have an identity in the Lord.
We are the salt of the earth
Salt has certain properties that if you remove them, then it stops being salt. The same goes for us Christians, we are the salt of this earth, whe are the ones who do this world to make sense. We are in charge of transmitting the message of salvation for the lives of the inhabitants of this world and that is precisely why Jesus tells us that we are the salt of this world:
Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.