Jesus said "He who follows Me shall not walk in the darkness, but shall have the light of life."
This is a promise to those who follow Him and are His disciple. If you want to have the light of life, then you must walk with Him. If you are walking in darkness and are lost and oppressed, then leave every thing else and follow Him.
Walking with Jesus means being a disciple. This means you go where He goes and do what He does.
It is not enough that you go to church each week or got baptized when you were 8. If you are not following after Jesus by the Spirit of God, then you are not a disciple and are walking in darkness.
The concept of light and life are intertwined in the Bible. The first thing that God created was light. Then God created life: Living plants and animals and finally man. Light is essential to life.
Conversely, the Bible tells us that the life of God brings light to all men: "In Him was life, and that life was the light of men ... enlightening all men."
Light also is used to mean understanding: Thy word is lamp unto my feet and light unto my path. There is the true light, light that brings true understanding and Truth. There is also a false light. The Bible tells us that the devil presents himself as an angel of light.
Which makes sense, because God dwells in unapproachable light. He has all understanding and truth.