To call ourselves Christian is to bear the name of Christ. With it comes the responsibility to witness to what that name means in life. Jesus spoke about putting a light on a lampstand to give light to the house. We are to be that light.
Proper light makes everything look different.
It shows how the polished furniture shines, as well as the dust on the shelf. Through Christ we are to show the light of God's life, pointing to what is good, and showing what needs to be cleansed. This happens first in us, and then as a witness to others as we live our Christian lives daily. You are a witness for Christ.