Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life.

John 8:12

There are few different ways in which Jesus is the light of the world.

He is the source of natural life for all mankind. Everyone owes their existence and continuance to Jesus Christ

All things were made by him; and without him was not any thing made that was made. In him was life; and the life was the light of men.

John 1:3-4

Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds; Who being the brightness of his glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high;

Hebrews 1:2-3

He is also the source of all true knowledge and wisdom to men.

The statutes of the LORD are right, rejoicing the heart: the commandment of the LORD is pure, enlightening the eyes.

Psalms 19:8

Both of these positions (as well as others) are correct but I think Jesus is making a more direct statement regarding the fact that He is the Messiah and is the source of life and wisdom to all the elect of God, not just among the Jews but among the Gentiles as well.

I the LORD have called thee in righteousness, and will hold thine hand, and will keep thee, and give thee for a covenant of the people, for a light of the Gentiles; To open the blind eyes, to bring out the prisoners from the prison, and them that sit in darkness out of the prison house.

Isaiah 42:6-7

Jesus is saying the same thing in His conversation with Nicodemus. 

For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved.

John 3:16-17

To a Jew, the term world referred to anyone who is not a Jew, in other words, a Gentile. God sent His Son, Jesus, to die for God’s people among the Jews and the Gentiles.

Thus, Jesus came to not only give life to the Gentiles but to give light, or understanding, about that life they have been given.

But is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel:

2nd Timothy 1:10

For those in liberal theological circles, statements such as this tear down the idea that Jesus never claimed to be God. That is exactly what Jesus is doing here. All we have to do is look at the reaction of the religious leaders of the day. They thought Jesus was claiming to be God. Why? Because Jesus was claiming such! He was declaring openly there in the public area of the Temple (John 8:20) for everyone to hear. “I am the Messiah. I am the Son of God. I am God!”

Incidentally, there are old writing of Jewish Rabbis that show the title “Light of the World” is one the Pharisees in particular liked to call themselves. We can see from their actions in the Bible and their iron grip of the people that they felt they were the only ones with the “true knowledge of God and salvation.” It had to really fire them up that Jesus was taking their title for Himself!

Further, look at the drastically different approach of those claiming to be the light of the world and the One Who actually is. They claimed they had all knowledge but they kept it to themselves and did not help the people. They used the Bible to strengthen their positions in society and reputations. Jesus did not do this. He was and is the source of wisdom and He freely gives to those who ask.

If any of you lack wisdom, let him ask of God, that giveth to all men liberally, and upbraideth not; and it shall be given him.

James 1:5

What a loving Shepherd we have!

It would behoove all those claiming to be ministers of the gospel to act like ministers and not “scholars of the Bible.” God gives men understanding of His word so that they can feed the people of God and comfort them. True preachers are not celebrities. They are servants of God and the people to whom they are instructed to teach and feed.

Feed the flock of God which is among you, taking the oversight thereof, not by constraint, but willingly; not for filthy lucre, but of a ready mind; Neither as being lords over God’s heritage, but being ensamples to the flock.

1st Peter 5:2-3