I do a routine, with or without a helper planted in the crowd, also using d'lites, that is based on "Bad thoughts". Essentially it is a discussion of sin, that allows me to explain what is sin, and what God thinks about Sin, the result of sin, etc, that revolves around picking "bad thoughts" out of the air (red lights) and I use a couple of other props with it as well, when the situation is right. The props I use are a small shot glass that blinks a nice matching red light when put down hard, it then blinks for about 15 seconds and then goes out totally. And I use a red laser pointer. I grab the shot glass and chase down one of those "bad thoughts" to keep them from becoming sin. Temptation is not a sin, but acting on t, can be. And then I slam the glass down on a table near a spectator, and the light blinks, and I make a joke about the bad thought trying to get out and get into my head. And then the light goes out, so I grab the shot glass look into it, see nothing, drop it into my pocket and start again looking for the bad thoughts. I then shine or have my helper shine the laser pointer at a place onteh wall, and I try to grab it, and it goes higher than I can reach. And then it comes back down, and I grab it, showing it inmy hand, and I talk about keeping the bad thoughts out of your mind, and bad words out of your ears. Why should we keep them from going in,? Becuase if they get in, they will come out! Where, your mouth, and I put one light "in my ear" and I immediately show it then coming out of my mouth. I put that one in my other ear, and once again, it immediatly comes out of my mouth.
Bad thoughts, Bad words. Bad, Bad Bad. You get the idea. You don't have to use the laser pointer or the lighting glass to do a version of this routine. I have done it totally alone with only the d'lites and done it with my helper, and we throw the lights back and forth. And I do it with the props as mentioned.
For a very simple effect, you can also take "bad thoughts" from other people's heads, and out of the air, and go around, and keep getting them, adn keep putting them into a paper bag, amking it sort of a light based miser's dream.....You might keep going back to a certain person, shaking your head, as they seem to have a lot of bad thoughts. (Be sure to make it a joke, and maybe even have yourself be the one who continues to have the most bad thoughts, so you don't embarrass someone else) But once you get all the bad thoughts collected and thrown into the bag, you can show what happens to bad thoughts that don't get acted upon. They just go away.... "So make sure that you get rid of those bad thoughts before you act on them and they become sin."