But light also reveals that which has been hidden by shadows, and we don't always want these things to be revealed, the things we struggle with, the things which we do when no one else sees (though our internet provider does). Light brings life but it also reveals that which needs to change. At times we do not feel like we can change, but the light has overcome the darkness and has been tempted in every way just as we have but is without sin. I heard a great definition of sin today:
Colwell goes on in his book The Rhythm of Doctrine to say that we only know what true humanity is meant to be in the light of Christ. All other expressions of it fall short however noble or heroic they maybe. Bonhoeffer calls Jesus the man for us, if you haven't read any Bonhoeffer then read some, especially the Cost of Discipleship, it might seem an impossible thing to live a life like this which is why Christ was the man for us. We can live this authentic life which was intended by the Father, lived by son and is outworked in us by the Holy Spirit.
"Sin primarily is our failure to do that which ought to be done, our failure to love God utterly and to love one another in reflection of that love for God" (Colwell, 2007, 65)
When light shines it changes that which it comes into contact with.