Ok, I think you're thinking of Catholicism...
That's quite true.
You're talking about Catholicism. I'll be honest here, most non-catholic denominations really don't know what to think about half of what you believe, aside from knowing that some beliefs in the Roman Catholic church were created as side effects of a power grab in the Middle Ages. I find some of the theology here... dubious.
I'd like to second that.
One word. Exegesis. Try it.
That's Catholicism. Again.
Context. It's important. Christians weren't around yet. Deuteronomy was part of the Torah, written to the Jews. Deuteronomy 17 was specifically telling the Israelites to kill those
among their own that were hateful towards the judge or priest in the court case. It never spoke of the Gentiles.
As for the original question; I believe there are things outside of the physical realm. I don't know if you'd call what I believe in "ghosts" per se, but I'm sure demonic interactions/encounters are often thought to be "ghost encounters" by the individuals involved.
They tend not to appear in first-world countries. If they were appearing right and left in the streets of D.C., people would be freaking out. Most people have forgotten about the possibility of a God. If you were the devil, why would you want to remind these people that there could be a God when most of them think they're perfectly fine without one?
I have heard stories of these things happening in third-world countries. Very few of them (could count them on my fingers), but the ones I can remember hearing about were eyewitness accounts from otherwise quite mentally stable individuals.
Now, I do think there are
plenty of incidences of people using "ghosts" or "demons" to explain away simple ignorance. I wouldn't be surprised if almost all recorded "ghost/demon encounters" were just ignorance-induced. But using this as proof against the existence of spiritual beings is an example of "
the fallacy fallacy."