The Church is the salt of earth (IRENAEUS, CLEMENT OF ALEXANDRIA, ORIGEN, CYPRIAN).
There are important characteristics about salt, that it stings and disinfects (METHODIUS).
More importantly, the Lord warns us that the salt can lose its saltiness. Salt preserves meat as Christians preserves the world (ORIGEN).
We are commanded therefore to be salted, since we will be convicted by our savor (IGNATIUS).
Our good works make us the light of the world (TERTULLIAN).
The light of the world is the church (ORIGEN).
We give light by proclaiming the Lord's teachings (CLEMENT OF ALEXANDRIA, TERTULLIAN).
Since God made man a free agent, possessing his own power, to obey the commands of God voluntarily, we ought to let our light shine by doing good (IRENAEUS).
Let your works shine (CLEMENT OF ALEXANDRIA, TERTULLIAN, METHODIUS).