It is important with this skit that you prepare your audience. Ask them not to join in singing until invited by an actor.
Begin with the room complete dark or at least very dark. 3-4 actors enter each with a lit candle and singing “This Little Light Of Mine.” They stop in front of the audience and continue to sing. From the side comes a dark figure (someone dressed in black and face covered) and mills around the actors in a stealthy manor (this person can represent the devil). The dark figure blows out one candle. That actor stops singing and lowers their head. One at a time the dark figure blows out the candles and the actors follow suit. Once the candles are blown out the dark figure leaves.
After a short pause of silence another actor comes in from the side with a lit candle singing “This Little Light Of Mine.” They light the candle of one of the actors who then lifts their head and begins singing again. They then light the candle of the next actor and so on until all actors are singing again. Invite the youth to join in the song as well.
You can end there or add this next piece. Before beginning the skit have a large mirror laying in the middle of the room with one large candle in the middle and enough tea lights for everyone. Have 2 actors with candles stay in front after the skit and light the large candle. Then invite each youth to make a physical statement (there are lots of statements to choose from) through lighting their own candle. Then with quiet music being played or sung allow them to come up, light a tea light from one of the actors, and place it back on the mirror.
We did this entire activity at a youth retreat and allowed the kids to sit as long as they wanted in silence. Many stayed for around an hour praying.