The Light of the World

What does it mean the Jesus Christ is the Light of the World?

D&C 88:6-13 talks about Christ’s role as both physical and spiritual light:
"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…
"He is in the sun, and the light of the sun, and the 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."

Just as we need light to sustain our physical life, we need light to sustain us spiritually as well, and Jesus Christ provides that light for us. A testimony of His role as the Light of the World helps us know that we will never have to remain in darkness. There will be trials and times that seem dark, but we can be assured that “weeping may endure for a night, but joy cometh in the morning” (Psalm 30:5)

Henry Wadsworth Longfellow wrote a poem entitled “The Rainy Day” that speaks of the dark times we sometimes go through, but at the same time, offers reassurance that even in the darkness, there is light.
The Rainy Day
The day is cold, and dark, and dreary;
 It rains, and the wind is never weary;
The vine still clings to the mouldering wall,
But at every gust the dead leaves fall,
And the day is dark and dreary.

My life is cold, and dark, and dreary;
It rains, and the wind is never weary;
My thoughts still cling to the mouldering Past,
But the hopes of youth fall thick in the blast,
And the days are dark and dreary.

Be still, sad heart! and cease repining;
Behind the clouds is the sun still shining;
Thy fate is the common fate of all,
Into each life some rain must fall,
Some days must be dark and dreary.

Just as Longfellow explains that “Behind the clouds is the sun still shining,” we can know that in our lives, the Son, even the Son of God, is always there, with His light shining to illuminate our lives. As Mosiah 16:9 says, “He is the light and the life of the world; yea, a light that is endless, that can never be darkened.” Nothing can extinguish His light. As we try to live by His teachings, we can know that, He is “come a light into the world, that whosoever believeth on [Him] should not abide in darkness.”