“In him was life; and the life was the light of men.”
John 1:4

In him; there is life and whoever has him, has life- that very life he lives by. Jesus had said:
“For as the Father hath life in himself; so hath he given to the Son to have life in himself;” John 5:26
This means the life in him, is the life in God and when you receive him, you automatically receive the life in God, that God-life that you receive supplants the human life you once lived with, this means you are no longer alienated from the life of God, on the contrary, you now sit, talk, walk, exist on the earth with a different type of life: [Ephesians 4:18]
And one of the first things he mentions is: receiving that life means receiving light; the first step of receiving knowledge of how to live on the earth. Just as you boldly declare you have and live by the life of God, similarly realize and declare that you should not walk in darkness but have divine understanding at every given point in time.