Some of this is easy. If you wake to find a living corpse hovering over your bed screaming, "Be gone from this house!", you should reply, "Got it. I'm out."
But it really shouldn't come to that. Chances are there were earlier warnings.
At this point, it's one you can solve with a real estate agent.
If they're normally bookish and introverted but suddenly they're giving emphatic, detailed accounts of being dragged out of their beds in the middle of the night by the bad lady who lives in the painting, that should alarm you.
Ask some questions.
If you see a 200-year-old Nun foaming at the mouth and levitating and the end of the hallway, don't just tell your spouse you saw "something."
Be specific. *Tell her about the Nun.*
Then ask a series of pointed questions about how they just got those scratch marks.
Obvious, right? The problem is someone will say it "won't matter" for some reason.
You know what? Test that theory. Go to Denny's and just keep ordering breakfast. Gotta be safer than sleeping in the depression-era orphanage you happen to be renovating.
There's usually a point in these movies where the last remaining victim decides to fight back, but by then she's got no help.
Make your last stand *before* your wife slowly walks into the woods and comes back speaking Latin.
Run drills. Prep for likely scenarios.
*Do not* just go to work and come home and watch TV until the lights start flickering and a child's laughter emanates from the basement. Now you are on defense, and the kid knows it.
You've been nice to your neighbors for years. You should feel fine making a one-time request for their help in battling a long-dead priest by luring him into a nearby corn field and re-opening the portal at the precise moment of the eclipse.
And stay safe this Halloween!