The born again believer is in Christ and should have a lifestyle that reflects the light, righteousness and truth that is inside of them. The Ephesian believers should be reflecting the light that Christ is shining on them.
"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) find out what pleases the Lord."
Paul identifies why the Ephesian believers are NOT reflecting the light shining on them from Christ. Many of the Ephesians have been deceived by empty words (Eph. 5:10), so Paul says "find out what pleases the Lord," and "understand what the Lord's will is." In other words, study the truth and stop listening to empty words that some claim to be from the Word of God. Due to their lack of knowledge of the truth the Ephesians cannot discern what the Lord is doing in their lives. Paul tells them to live "not as unwise but as wise" and "do not be foolish, but understand what the Lord's will is."
Many of the Ephesians look, live and act just like the people who are still dead in sin and lost in darkness. Paul uses the image of a sleeping person who comfortably deep in sleep in a morgue among the dead bodies. This person who is sleeping in the morgue looks just like the dead bodies, but there is a vast difference. The sleeping person is alive! They can be awaken so that they can stand up and walk out of the morgue.
Paul compares the Ephesians believers as "sleepers" among the "dead." If the Ephesians will rise up from among the dead, Christ light will begin to manifest through them. The light and life the Ephesians have on the inside will be reflected in their lives and in their world as the fruit of light: goodness, righteousness and truth:
"Wake up, sleeper,
rise from the dead,
and Christ will shine on you."
How can these born again sleepers rise from among the dead? They can find out what pleases the Lord and understand what God's will is. In other words, they can learn the truth that comes from the same source as the message of salvation: The written word of God, the Bible.