Ghosts and demons may be connected. Or, they may not be.
Let’s say ghosts are spirits of some people who once lived among us.
By contrast, demons never lived as humans. They are very different kinds of beings.
Some religions don’t believe in Satan, the Devil, or similar entities.
Usually, those religions don’t believe any entity could be a significant threat to Deity.
In fact, among those religions, it’s heresy to believe in a supremely powerful, Devil-like being.
However, if spirits exist, some seem to have better intentions than others.
At extremes, some spirits may be benevolent and described in angelic terms. Others seem to thrive on evil and malicious behavior.
Many investigators use the word “demon” to describe energy representing something profoundly malicious. It’s a relative term with a lot of variations.
Ghosts can be pranksters, or even angry
First of all, ghosts aren’t always well-behaved. Some may be pranksters or mischievous, like poltergeists. Some may be angry or territorial; those ghosts can be frightening.
Nevertheless, there is a distinction between ghosts and demons.
Demons’ intentions seem dangerously different
Most first-person encounters suggest that demonic energy is intent on fooling us so we drop our defenses. Then, it attacks.
Crossovers may exist. Some ghosts were, and perhaps still are, under the influence of demons.
I’m not sure of that, but if a spirit seems malicious, I avoid it. If danger is possible, I leave.
I’d rather be too cautious than spend months — or even years — regretting a foolhardy moment.
I’ve listened to demonologists I trust, like John Zaffis and the late Father Andrew Calder. Their tales have been terrifying and convincing.
However, ghosts do not become demons, and demons do not become ghosts. So, there seems to be no direct connection between them.
Ghosts and demons are different kinds of entities in the spirit world. When they interact with us, their behaviors are very different.