Someone is manipulating my thoughts

I'm constantly being manipulated in my thinking by some evil spirit, whose sole purpose is to deceive me at all costs. Does someone have any advice on how to overcome this?

Hey, you provided very little information about yourself and the voice you wrote about. For example, how long has the spirit been present? Do you actually hear it or is it more like a voice in your head? In what ways does it try to deceive you?
The appearance of such voices, which are an entirely different thing from one's internal monologue, are usually serious. I have a few of them, the eldest has been with me since I was about 10, being 19 at present. My relationship with it has been a real roller coaster through the years, from a feeling close to infatuation, through fear, to dislike. I still struggle to accept it, but it probably formed from an anger that I was never allowed to express. It could be like that for you, in which case I would recommend trying to calm both of yourselves and listen to it, instead of trying to "overcome" it, as you put it, but as I said, you offered very little information about this voice.