The Gospel of Jesus Christ, and the infallible word of God. 

Remember that Jesus Christ is the Light of the World "I am the Light of the World", meaning that he is the reason of why all exists, that all is illuminated, and the reason of why we have the truth about God. We Christians who have been baptized, and so therefore have been untied to Jesus Christ in Holy Baptism, are also the light of the world as well. By the power of Christ's Baptism, Life, Death, and Resurrection, we bring Christ's light to the world, so that as many as possible can be saved, and have the gift of God's salvation, freedom, faith, hope, and his eternal Love, as well as the gift of the truth about God. So therefore, we Christians, being united intimately to Jesus Christ, are to bring Christ's Light to the entire world, bringing his Truth and Love to as many as possible, so that by the power of God the Holy Trinity, God can save as many people as possible, so that as many as possible can be with him, sharing his Love and Life for eternity. That's why Christ calls us the light of the world, and how we, as a city (The Church) built on top of the mountain (Jesus Christ) cannot be hidden, and so go forth and bring Christ's light to the entire world. Amen.

Remember this.