Christian graffiti

I have just started on a new project: Christian graffiti. How often have you been in a toilet stall in a public restroom and desired to post a Christian message to compete with the other types of messages scrawled on the wall? But, since you are a Christian, you know you are not supposed to deface property. The project I have started is to place easily removable stickers with Christian messages on stall walls. The janitor or anyone who is offended can readily remove the sticker and it does not leave a mark. (I'm using Avery name badges with messages printed by my laser printer.) If a message gets removed, you can just replace it later. There should not be anything illegal or unethical about this since you are not defacing property.