Tell them that your house has been officially and formally been turned into a church to reach those that Christ wants to save. The ask if they will join hands with you to help sanctify this new building that the LORD is using to bring ones into being "born again" etc etc throw as much Jesus Freak lingo in there as possible. This will prevent them coming back into your home.
Also for added effect, tell them that some in your group have noticed a aura around the building.
NJY