Anybody please tell me if demons are real cuase one day my friend was over then she went all syco and tried to kill me with a knife then when the thing came out of her she said why am I holding a knife then I told her the story

Your friend has problems totally unrelated to demons.

You need to stay away from this person before you get hurt and she claims the Devil told her to kill you.

You are aware she could be arrested, right?

Demonic beings are as real as you and I. I'm sorry to say this but if your friend has been possessed before by this being it is a good idea to move.

Short answer, yes, demons are very real. Now we can't necessarily go around blaming everything on demons, but they do have their place of blame. This very well could be that sort of situation.

Can we have a little more information? What set her off to go psycho? Besides trying to stab you, did she say or do anything else? How were you so sure something "left" her, besides that she came to?

Is you friend in to alternative religions or any aspect of the occult? Has she ever acted like this before?

Judy is right however, if this type of mood swing can possibly happen again, I'd be very careful around this person.