Then it really is Old Scratch knocking at the door.
Something of the forgotten John Carpenter movie, Prince of Darkness shows both the good and bad side of the supremely talented director.
The story is a beaut, a bit skew-whiff, but unmistakably Carpenter territory as Satan exists in some sort of parallel universe. How he manifests himself is narratively a bit tricky, but still it makes for good horror, especially as the old religious angle finds Carpenter - in the guise of Donald Pleasence - chortling away to himself in a way that Old Nick has been prone to do.
Cue bugs, green goo, zombies and a centuries old sect determined to keep Satan out of our world. The scares are many, atmosphere bubbling away (in time with another of Carpenter's pulse beat synth musical scores), while the finale has a genuine surprise up its sleeve.
Unfortunately the cast are playing second fiddle to the supernatural strengths, working from a script that doesn't sit at one with the screenplay, rendering the characters as uninvolving fodder. Yet be that as it may, it's still a film of delights, enough in fact to make it a top end entry on Carpenter's CV. 7/10