To be salt and light.

Matthew 5:13-16 (Amplified Bible)

     ¹³You are the salt of the earth, but if salt has lost its taste (its strength, its quality), how can its saltness be restored? It is not good for anything any longer but to be thrown out and trodden underfoot by men.

    ¹⁴You are the light of the world. A city set on a hill cannot be hidden.

    ¹⁵Nor do men light a lamp and put it under a peck measure, but on a lampstand, and it gives light to all in the house.

    ¹⁶Let your light so shine before men that they may see your  moral excellence and your praiseworthy, noble, and good deeds and recognize and honor and praise and glorify your Father Who is in heaven.