"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
Jesus is the light of the world. Jesus gives life to the world through His light. If you have "the light of life" you have eternal life in you. If you follow Jesus (go where he goes and do what he does) you will not walk in darkness. It's not that you cannot make a mistake or have an indiscretion or even commit a sin, but your pathway has been cleared; your way has been lit up. Jesus goes ahead as the light so that you do not have to walk in darkness. Without the light of Jesus you are guessing about your direction at best. That's why so many people that do not know Jesus have unfounded beliefs based on confused philosophies. They are walking in darkness.
It does not mean that they are necessarily doing evil things it simply means they do not have a lighted path. But from the perspective of having a lighted path, what business do we have dabbling in dark anything. Dark TV, dark books, Dark video games. Jesus comes and gives us life and lights our path. We should respond by staying true to our calling, i. e., a holy life. This life is very short and it should be a goal to live it in the light.