so I guess there's no harm in keeping it up there.
It's only harmful if you consider it harmful.
On the plus side, it might come in handy someday, because you never know when you might be attacked by a vampire.
That said, it would probably be a good idea to also hang a magen david up there, in case you're attacked by a Jewish
Don't even get me started about what a pain in the neck Buddhist vampires can be...