When you said
Not trying to start any sort of religious debate
I'm guessing you think Christians do not believe in ghosts!
I am a Christian, but goodness sakes, the Bible speaks of ghosts and spirits! The Holy Ghost is part of the Holy Trinity! So I can't not believe, though I personally have never had an experience outside the leading of the Holy Spirit. My youngest grandson, Nick, had an experience within weeks after his brother, Nathan, left us though, and his recount was as real as real could be. I don't doubt for a moment that this child saw the spirit of his brother standing along side Jesus, and that Nathan reassured him that he is fine now. He was awake and riding in the car so it wasn't a dream. Nathan told Nick another time that all you had to do to see him was "look up and believe!". Nick recounted it so matter of factly. It's chilling to think about. Wish I could see my boy again. I will someday, just not now.
What an interesting subject.
Now as a Christian, I also believe there are dark spirits out there that we ought not be messing with. Satan has his legions too and they aren't good. I'm sorry! I just had to get that in!