"You are the light of the world. A city on the hill cannot be hidden. Neither do people light a lamp and put it under a bowl. Instead, they put it on its stand, and it gives light to everyone in the house. In the same way let your light shine before men, that they may see your good deeds and praise your Father in heaven" (Matt. 5:13-16).
God has selected you to be the light of the world. You cannot make yourself be the light of the world. "The God who said, 'Out of darkness the light shall shine and' is the same God who made His light shine in our hearts, to bring us the knowledge of God's glory shining in the face of Christ" (2Cor. 4:6).
This is a picture of discipleship. Jesus, who is the light of the world, transforms us into the light of the world. We are light because we are in a spiritual relationship with the light of the world. He draws us to follow after Him, and says, "Whoever follows me will have the light of life and never walk in darkness" (Jn. 8:12).
Our focus must continually be in the light, humbly trusting Jesus to reveal the light through us. My focus is on following Jesus wherever he leads.
Since Christ is the source of light, we must reflect Christ's love, compassion, forgiveness, longsuffering, and etc. in this dark, fallen world.