Satanic sacrifices aren't scary on their own. They need sound and ambience to build up the fear factor. Same can be said for torture. Make the player feel part of that environment
Don't attempt any quick scares unless the player is already fearful of their environment. This is why sound and ambience is so important;
Personally, I immerse myself in amnesia, so I take note of where almost everything is, so if I turn my back and then suddenly things are missing or added (Like a suit of armor or something), I find that scary.
Its hard to see the truth when you've been blinded by lies.