When I was 16, my family moved into an old house in the country. For the first week nothing happened. Soon, there were strange noises in the attic, and streams of smoke would just appear in front of us, then disappear. I used to wake up in the middle of the night with the feeling of someone sitting on my chest with their hands around my throat. I found out later that my mom was having the same experience at night.
My parents talked to one of the elders about it, and went through the house throwing away all items that were purchased at a yard sale. My dad threw away all of my Billy Idol cassettes because they had a cross on the label. He actually threw away my "Legend Of Zelda" game because it had magic in it.
Still, after throwing away everything they thought my be "inviting" the demons into our home, there were more unexplained things happening.
I was in my little brothers room talking to him when we heard a rattling sound. We looked up on his dresser and his penny bank was shaking like crazy. It started sliding across the dresser and fell off.
There was an antique doll that my mom had purchased at a yard sale, that we threw out into the garbage can outside. Later that night when I went to bed the doll was laying on my pillow.
Needless to say "Calling on the name of Jehovah" never helped, not even when I was being physically attacked.
We eventually moved.
My parents believe that the house itself was demonized.
Personally, I believe that we simply lived in a haunted house. Call it a ghost or a poltergeist if you want, but I know for a fact that SOMETHING was living in that house other than my family.