Harm children?

If not by frightening a living being to death, causing a heart attack, how?

This remains to be examined.
Perhaps there really are such things as demons, beings from Hell who are corporeal, who are capable of evil. A being that would want to interact with a human, but if they chased them off, the creature would have no one to harm...that is what does not make sense.

Like I would believe in demons from Hell appearing in the real world.

But, if people claim to see angels, feel angels, have angels speak to them, I guess their counterpart in the netherworld could exist.

Or those who THINK they see angels are capable of THINKING demons exist also.

For the Angels, they only assist in goodness. Demons, however, seem only to do bad things. Do they assist in evil? Do demons cause humans to do bad things, or are humans perfectly capable of doing bad things on their own with no help from otherworldly creatures?

Ghosts, on the other hand, can't do much of anything since they can't actually form into anything capable of holding something or ripping their fingernails across living flesh.
They're images, totally non-corporeal. If they cause rapping noises, I can't figure out how. If they move objects, how can they manage that? I can see the chill factor, the heat factor, perhaps, the blurred images, the sounds, maybe. But touch, other than the sensation of cold, I just do not know.

Since I am currently working on rewriting a previous ms. which deals with ghosts, I have been studying ghostly behavior from written records and watching several shows on television that pertain to ghosthunting.
Ghost Hunters on the Sci-Fi channel comes closest to believable. The Haunting series on Discovery and it's assorted clones, is total crap. The psychic night on We is interesting, but doesn't purport to track ghosts or have anything physical to do with them. There are psychic mediums who claim to talk to the departed souls. They're interesting. They don't tell about being touched or struck. But, perhaps, there is more to this ghostly business, if one were to incorporate the angel/demon theory.

Yes, this all sounds more like an episode of Buffy the Vampire Slayer than me. Or reality.
But it does give me pause to wonder about this touching business and ghosts.
My male ghost character has the ability to manifest portions of his body (his hands) into something solid enough to touch. They can also apport things... move them by the power of their minds. Would they scratch a child, harm an innocent? No.
They're not that type.

They're Caspars.

Not Slimers.