If you're in your own home, no need for pretence! Anybody on your property, uninvited, is actually trespassing.
If you don't want to open your door, THAT is your prerogative. There's nothing written anywhere, that you're bound to open door, except to Police!
In my high set home I could see out, but door-knocker couldn't see in. That way I could easily decide what I'd do.
Cultists' were given very short-schrift from upstairs window, in no uncertain words!