Take no part in the unfruitful works of darkness, but instead expose them.
It turned out that there were two of them. Thieves had broken into our big garden shed — my study! It was very late and very dark but we saw flashing lights in the shed. The first thing we did was to put on the bright light that lights up the garden and when the thieves became aware of the light they knew they were discovered. Out of the shed they bolted and leapt over the garden fence and ran away as quickly as they could. They only tried to steal one thing and even that they dropped in their hurry to get away. So for them it really was the "unfruitful works of darkness" on that particular night. The light exposed their evil deeds.
"Works of darkness" are sinful things which a Christian should have nothing to do with — we have not only to avoid them but to show how shameful some of these 'works' are. We have to shine the light of the Gospel on them both to make sure our own hearts and lives are pure, and also to show to others how wrong such sinful practices and thoughts really are. "It is shameful even to speak of the things that (are done) in secret" (verse 12).
If we belong to Jesus we have a great responsibility to have lives that are true examples of Christlikeness because so many people do not know the Bible and do not know the moral values that make life worth living and are pleasing to God.
Dear Lord, help me to look carefully at how I walk both before you and those around me. Amen.