Brett asked: “In Luke, when Jesus said I am not a ghost, does this mean that ghosts exist?
In Luke 24, Jesus appears to His followers after rising from the dead. This was a bit startling and hard to believe. To comfort and encourage them, Jesus said this in verses 38-40:
And he said to them, “Why are you troubled, and why do doubts arise in your hearts? See my hands and my feet, that it is I myself. Touch me, and see. For a spirit does not have flesh and bones as you see that I have.” And when he had said this, he showed them his hands and his feet.
To contrast His bodily resurrection with something that might have only been spiritual in nature, Jesus clarified that He was not a spirit, or "ghost" in your translation. His resurrection body was physical and He could be touched.
The answer to your question really hinges on definitions.
Yes, there are spirit beings. They are just as real as you and I are. Angels are spirit beings. They exist in a spiritual dimension that you and I cannot currently see. The only time humans have seen angels is when God performs a miracle and allows angels to appear to humans in bodily form. Most of the time, we cannot see them. But they are real, and they are at work accomplishing God's will.
However, sometimes people use the word "ghost" to refer to dead humans who are somehow roaming the earth, perhaps causing some sort of mischief or "haunting" people. Sprits or ghosts in that meaning do not exist.
When a person dies, their spirit leaves their body and goes to either a place of torment, or a place of great joy and gladness. Human spirits do not roam the earth, they do not haunt people, and they do not appear or speak to people. Anything that appears like that is a deception.
So yes, spirits do exist, but in a specific way.