Dear Violet,
In my own experience I have to echo gsx's opinion . . . since leaving christianity none of my spiritual experiences or revelations have been negative, much less malevolent.
I was just commenting the other day in fact that the only demonic encounters I had heard of were from people that believed in demons (christians etc.)
Hylander said something to the effect that encounters people attributed to demons were in fact misinterpreted encounters with ghosts. My opinion is along the same bent but I actually do not believe in ghosts or demons, I look at it pretty vaguely.
I think we are too quick to assign characteristics and personalities to things we don't understand. Yes I believe there is great and mysterious power in the universe and I think we can access it, however I think it is neither 'good' nor 'bad' until manifested through the filter of our personal belief system.
In short I say believe what you want, just know that what you believe is likely what you'll get . . . so make it a good thing.
take care,
raven101