In our family carpet cleaning business we offered a special service for removing pet urine odors. To show potential customers their need for the service, I would darken the room and then turn on a powerful black light. The black light caused urine crystals to glow brightly.

To the horror of the homeowner every drop and dribble could be seen, not only on the carpet, but usually on walls, drapes, furniture, and even on lamp shades. One homeowner begged me to shut off the light: "I can't bear to see anymore. I don't care what it costs. Please clean it up!" Another woman said, "I'll never be comfortable in my home again."

The offense was there all the time, but it was invisible until the right light exposed it. It would have been cruel to show customers the extent of their problem and then say, "Too bad for you" and walk away. I brought the light so that they might desperately want my cleaning services.

In the same way, God shines the light of his commandments not just to make us feel guilty and leave us that way. He has a cleaning service to offer—salvation through Jesus Christ.

You can watch a short video example here