In some incomprehensible way not only is the Savior the light of the world as the perfect exemplar and the life of the world in that his atonement yields immortality and eternal life, but his power also ensures life and light to all creations (see D&C 93:9). He is the source of all light, life, and truth (see Ether 4:12). See also Mosiah 16:9; D&C 10:70; D&C 45:7; D&C 50:24, 27.
“I Am the Light and the Life of the World”
This declaration of the Savior, which was also understood by his disciples in the Old World (see John 1:4-5, 9; John 8:12) should not be viewed as merely symbolic. This statement is not only a powerful declaration of his divine sonship and of his being the fulfillment of ancient prophecies concerning the true light of the Messiah, the Enlightener (see Psalms 27:1; Psalms 43:3; Isaiah 49:6), but is also something more. The Savior, in a very literal way, is the light and the life of the world.“I Am the Light and the Life of the World”
He that ascended up on high, as also he descended below all things, in that he comprehended all things, that he might be in all and through all things, the light of truth; which truth shineth. This is the light of Christ. As also he is in the sun, and the light of the sun, and power thereof by which it was made. As also he is in the moon, and is the light of the moon, and the power thereof by which it was made; as also the light of the stars, and the power thereof by which they were made; and the earth also and the power thereof, even the earth upon which you stand. And the light which shineth, which giveth you light, is through him who enlighteneth your eyes, which is the same light that quickeneth your understandings; which light proceedeth forth from the presence of God to fill the immensity of space- the light which is in all things, which giveth life to all things, which is the law by which all things are governed, even the power of God who sitteth upon his throne, who is in the bosom of eternity, who is in the midst of all things. (D&C 88:6-13.)