"for you were formerly darkness, but now you are Light in the Lord; walk as children of Light (for the fruit of the Light consists in all goodness and righteousness and truth),
trying to learn what is pleasing to the Lord.
Christians don't need to dwell on what they were before they came to Christ. We are no longer the embodiment of darkness, now we are bright shining lights, just as the Lord is a Shining Light. However, remembering the darkness from which we came does help us to live in thankfulness, with a desire to please the One who gave His life so that we could become "children of Light". "Paul’s argument is based upon a fundamental premise: Christians have undergone a dramatic transformation which is here described as having been transformed from darkness to light. In the Bible, salvation is never spoken of as a trivial matter. Those who are saved by faith in Christ are not merely improved, they are radically transformed. They have been delivered from death and given eternal life and have been saved from a life of sin to a new life which is characterized by good works (Ephesians 2:1-10." (Bob Deffinbaugh)