Devils and Demons

Every religion and word culture, has concept of  demons and demonic possesion.
If you're panicked, you're open for demonic possesion.
If possessed, he/she will flinch at the name of god.(latin:christo) 

An exorcism that's gotta work is: The Rituale Romanum
It's two parts: 
First part expels the demon from victim's body, it makes it manifest, which makes it more powerful. It doesn't need to possess anyone, it can just wreck havoc on it's own.
Second part sends the bastard back to hell, once and for all.
Demonic possesion leaves behind sulfuric residue.

Demons, they don't want anyting; just death and destruction for it's own sake.
For example :
Accordding to Japanese belief certain demons behind certaing disasters; both man made and natural.
One couses earthquakes, another couses diseases...   
                

There are signs (omens) to demon precense:

• Cattle deaths,
• Temperature fluctuations,
• Electrical storms.

And they leave behind sulfur trace.