I haven't seen mention of "The Evil", also called "Cry Demon" with Richard Crenna. Victor Buono plays Satan, sitting on a throne, dressed in white, under the basement. It's been a looooong time since I've seen it but I can still see clearly Andrew Prine running a circular saw through his hand.
Moral of the story: If you find a door on the floor of the basement in a house with a spooky reputation, and said door is locked and secured with a large cross--DON'T TOUCH THE CROSS!! Duh