For you were once darkness, but now you are light in the Lord. Live as children of light (for the fruit of the light consists in all goodness, righteousness and truth) and find out what pleases the Lord. Have nothing to do with the fruitless deeds of darkness, but rather expose them. It is shameful even to mention what the disobedient do in secret. But everything exposed by the light becomes visible—and everything that is illuminated becomes a light. This is why it is said:
“Wake up, sleeper, rise from the dead, and Christ will shine on you.”
Be very careful, then, how you live—not as unwise but as wise, making the most of every opportunity, because the days are evil. Therefore do not be foolish, but understand what the Lord’s will is.
Ephesians 5:8-17 (NIV)